Newbies buying a 1900s Edwardian cottage, valuation, surveyors, builders, damp advice

[topdog91]

Hi all, first post so please be gentle.

We're considering buying a circa-1900 Edwardian cottage. It is not listed, but it is in Green Belt, and we have submitted a pre-planning application for a modest rear extension.

We are new to traditional buildings and are finding the advice quite confusing. Some people say they understand period properties, breathability and damp, but then quickly talk about chemical DPC injection, damp specialists, gypsum plaster, modern tanking, etc. Others say old cottages should be treated very differently, with focus on ground levels, rainwater goods, ventilation, lime plaster, breathable materials, roof/chimney defects and undoing bad modern interventions.

The cottage is one of a small row next to an old farm. It has clearly been altered over time. There is an awkward later first-floor/box-room extension where the roof geometry is poor, with intersecting roof forms/gables intruding into the upstairs space. There is also a collapsed lath and plaster ceiling in one bedroom, possibly where a chimney stack or chimney breast was removed or badly supported.

It also has old private drainage/cesspit arrangements. The other cottages apparently have treatment plants. There are possible damp-related issues, including external ground levels/materials and a black painted material at the base of some walls. We do not yet know whether the damp is due to real structural defects, trapped moisture, neglect, bad modern repairs, failed rainwater goods, poor ventilation, or something else.

We have had a practical builder look at it and he seemed to understand the roof/upstairs issue well. His suggestion was that if we extend, we should also take the opportunity to remove/rework the existing rear roof and properly solve the compromised bedroom/box-room layout. That made sense to us. However, he also mentioned damp injection, which made us nervous, as we keep reading that this can be over-prescribed in older buildings.

At the moment we are trying to work out the right team and sequence before committing too far. Our current thinking is:

• Get a surveyor who genuinely understands traditional buildings, damp, timber, breathability and old materials. (We've even had conflicting advice about whether a 1900s Edwardian cottage requires such a surveyor - one friend said any surveyor will do as they aren't old in the grand scheme of things.)
• Get a structural engineer specifically to look at the roof/chimney/ceiling collapse issue.
• Get a drainage camera survey for the cesspit/septic/treatment plant situation.
• Use a competent general builder for the main refurbishment and extension.
• Bring in heritage/traditional-building advice for the sensitive parts, such as damp diagnosis, lime plaster, breathable finishes, high external ground levels, and undoing inappropriate modern repairs.
• Avoid chemical DPC injection unless there is a proper diagnosis and a convincing reason for it.

We are also struggling with valuation. The asking price has already been reduced, but we do not yet know what work genuinely needs doing, what is urgent, what is optional, and what it will cost. We do not want to under-offer unfairly, but we also do not want to pay a price that assumes a simple refurb when the building may need roof, chimney, drainage, damp/fabric, heating and extension work.

What would experienced period-property people suggest?

Specific questions:

1. How do we identify a surveyor who genuinely understands traditional buildings, rather than just saying they do?
2. Is RICS Level 3 enough, or should we prioritise a conservation/traditional-building specialist?
3. Is it sensible to use a normal builder for the main works, while taking specialist heritage advice on damp, plaster, breathability and old fabric?
4. Is chemical DPC injection ever appropriate in a cottage of this age, or should we treat it as a warning sign unless very clearly justified?
5. What should we do before purchase to understand the collapsed lath and plaster ceiling and possible chimney/roof issue?
6. How would you approach valuation and offers when the real scope of work is still uncertain?
7. Are there any particular red flags in a circa-1900 cottage that we should be looking for?
8. Any recommendations for surveyors, engineers, drainage people or builders in Hertfordshire, North London or southwest Hertfordshire who are good with this sort of property?

We are not trying to make it into a shiny new-build-style house. We want to make it warm, dry, comfortable and practical, but without damaging the character or trapping moisture in the building.

Any advice would be much appreciated, thanks in advance and good to be here.

 

[paulc]

Specific questions:

4. Is chemical DPC injection ever appropriate in a cottage of this age, or should we treat it as a warning sign unless very clearly justified?

I think there is sufficient evidence from countless properties that have had the injected DPC and tanking done that shows these "cures" only mask the problem for a few years. If you stop for a few minutes and apply a modicum of critical thinking to the "science" that the damp treatment companies spout, you end up realising it is all one big con. For example:

• The DPC has failed - Really ? Along the whole length ? It is buried within a wall, so well protected from damage and environmental attack.
• Waterproof render/plaster applied to a height of 1.2m - Why is it always 1.2m regardless of the type of brick/stone the building is constructed from ?
• The chemicals in these DPC rods spread out through the bricks and form a waterproof DPC - How ? Why ? Where is the independently reviewed research ? How does the type of brick/stone affect the migration of the chemicals ?
• Protimeter (damp meter) says xx% moisture in the wall - These meters are only designed to be used on untreated timber. How can they give a specific reading on a wide variety of materials when (for example) salt content can throw the readings out ? Meter reading says 80%, 90% - You'd be seeing water running down the walls at that sort of level.
• Warranty of 20 years - Why is it you are returning to the same property after 10-12 years claiming current problems are due to condensation and then carrying out another round of injecting & tanking ?

As for a collapsed lath & plaster ceiling, that could be the result of a number of causes. Moisture ingress resulting in nails securing the laths rusting away. Impact damage from someone putting their foot through the floor.
When selecting builders, ask them how much cement they would add to a lime mortar or know what a churn brush is. The good ones won't use cement and can tell you just how a churn brush is used (compacting a mortar joint, not for sweeping up rubbish).

 

[Lacan07]

As Paul says the damp proof industry is a money generating farce by and large. The failed slate DPC in its entirety is my particular favourite, that always made me laugh. I think there's some well intentioned people in the sector, mainly independents, and the concept of the liquid DPC is sound but the application is often poor. In my opinion genuine rising damp is rare and high ground levels or concrete floors are often the cause of most damp issues.

I'm afraid you'll likely struggle to find sympathetic or knowledgable general builders and heritage traders are expensive. The majority of old house renovations are bodged and dare i say many properties can withstand the modern 'punishment' and chug along fine. Very often the only way to do things properly is to learn as much yourself as you can and get involved in the project.Curing an old house of damp doesn't have to be expensive but it can involve a lot of hard work!

 

[montyjohn]

People get way too concerned with damp. Whilst it can rot wood, cause wood worm etc, the underlying cause should be hard to fix. You just have to hope you;ve not caught it too late.

The physics is really straight forward.
If you don't have any leaks, and the walls can dry out, you won't have any damp.

We got our house really cheap as there was severe mould in almost every room. Gutter leaks for decades so saturated walls and not being heated. Everybody ran a mile.

The only fix we have made so far is install a central heating system (whilst it had radiators upstairs, the Rayburn wasn't powerful enough to heat them) and clear out the gutters.
Took several months to dry the walls out.

For now we have just put one coat of limewash on as a test. Think it needs to dry a bit more, and there's some work to do with salts coming thorugh.
This photo below shows what some heat, a bit of ventilation, and some basic maintenance and a coat of lime wash can do.



Now we were lucky, the joists aren't rotten. As there was no way to establish this until we bought the place it was just a risk we accepted.

I've got a few sagging lathe and plaster areas too. Form the ones I've been able to get to, some of the lathes have rotten into a powered. The rest seem fine.
You can buy stainless steel screws and large washers to hold it up, in a small recess. And just fill over it with lime putty. Not perfect, but it won't go anywhere and you'll not notice it ever again. Much easier, quicker and cheaper than redoing the lath and plaster.

I paid about £2500 for a heritage specialist survey. I think I went overboard. The guy was there all day, knew his stuff and I was with him for most of the day discussing the house, and that was valuable. But in all honesty, the things he noticed were things I had noticed anyway. I don't know if I would bother a second time. The argument is always it's a small % of purchase price, but £2500 is a lot of materials. I also realised I was going to buy it regardless.

A normal builder is fine, provided they aren't a know-it-all. If you're researching what the right thing to do is, you want a builder that will acommodate it. Not one that says, I do it this way and always have blah blah blah. They're out there.

My understanding of damp.

Water likes to spread out. If one area is 100% humidity, and another 20%, the moisture will want to migrate from the high humidity to the lower humidity area. In winter when it's wet and cold outside, 100% humidity outside is common.
Inside however, if you keep your house warm (you'll need to do this) and you keep it ventilated (you'll need to do this to) then the moisture in the walls will be drawn inside your house.

Provided you use materials like lime (no gypsum, cement, plastic paint, plastic wallpaper) then the wall will stay dry. If you try and stop water getting in, worst case it will blow off whatever you try and block it with, or your wall will just become saturated and your house will be hard to heat.

Keeping walls dry is harder if your gutters don't work, the ground level outside is too high, or any other leak. These should be fixed first. Heating is key, and some ventilation (you don't need a lot, just some).

Any attempts to DPC, tank etc do the opposite of the above and in my view, just make things worse

 

[Flyfisher]

Water likes to spread out. If one area is 100% humidity, and another 20%, the moisture will want to migrate from the high humidity to the lower humidity area. In winter when it's wet and cold outside, 100% humidity outside is common.
Inside however, if you keep your house warm (you'll need to do this) and you keep it ventilated (you'll need to do this to) then the moisture in the walls will be drawn inside your house.

Bear in mind that humidity is generally measured as 'relative humidity'. 100% RH just means that the air is carrying as much moisture as it can, but the actual amount of moisture will vary considerably with temperature. Thus, the air on a cold, damp winter's day might well be at 100% humidity but could be carrying less moisture than a hot summer's day at, say, 80% humidity. Also, air below 0c will be carrying no moisture at all, which is why a wet UK winter of 5c can 'feel' colder than -10c in the Alps.

So yes, keep the house warm but be aware that this will increase the moisture-carrying capacity if the air inside and is why ventilation is so important to allow this moisture to escape. I'm sure we've all seen examples of black mould on bathroom and kitchen walls because poor ventilation has trapped the airborne moisture, which eventually condenses onto a cooler wall and provides the source of freshwater needed for black mould to grow. It's a form of 'damp', but is certainly not penetrating damp or rising damp.

 

[topdog91]

Thanks all for the useful feedback so far.

We had a traditional-building surveyor visit today. One thing that has confused us is the ground floor construction.

The surveyor thought the downstairs floor might be concrete. A friend later suggested that concrete floors might possibly have been original for a property of this age, but I had assumed that concrete ground floors were generally later, especially in cottages.

So my questions are:

Could a circa-1900 modest cottage originally have had solid/concrete floors downstairs, or would suspended timber have been more typical?

Would it have been common to have a mix, for example suspended timber in front rooms and solid floor in kitchen/scullery areas?

If the floor is later concrete, how do we assess whether it is harmless, or whether it may be trapping moisture and contributing to damp at the base of the walls?

Should we be thinking about removing concrete and reinstating timber, or is that a bad assumption unless there is clear evidence the floor is causing problems (there may well be, waiting for the full report)?

We are trying to avoid both extremes: ripping things out unnecessarily, but also not keeping a modern intervention if it is damaging the building. Any advice on how to investigate this properly would be much appreciated.

 

[topdog91]

We have now had an initial survey/look-over done and are trying to make sense of it before deciding how far to proceed and what the property is really worth.

The house is clearly a project, but we are getting conflicting advice about how much of this is genuinely serious, how much is normal old-building stuff, and how much is “purist” versus practical.

Main findings/issues raised:

• The house needs substantial refurbishment, not just decoration.
• The rear of the house has an aborted/poor later extension, with awkward roof geometry and a compromised upstairs box-room/rear bedroom.
• One upstairs lath and plaster ceiling has collapsed, possibly linked to previous chimney alteration/removal or roof/structure issues.
• There are old private drainage/cesspit/septic arrangements. We would expect to replace this with a proper sewage treatment plant, subject to drainage survey/design.
• Some rainwater/drainage arrangements appear poor, with blocked gullies/manholes and water management issues at the rear.
• Some external ground levels/materials may be contributing to damp.
• There is black painted material (blackjack?) at the base of some external walls.
• Some pointing appears to be harder cement-type pointing on softer brick.
• The ground floors appear to be solid/concrete in at least some areas, possibly with a DPM. We are not sure if these are original, later replacements, or whether they may be affecting moisture movement in the walls.
• There is a mix of window types, including timber and PVC, and some single glazing despite the listing saying double glazed.
• Internally there are modern materials such as gypsum plaster in places, and the surveyor raised breathability/moisture concerns.
• There is some surface mould to rafters/roof areas, possibly a ventilation issue rather than structural timber decay.
• Heating, plumbing and electrics are likely to need major overhaul or replacement.

Our intended works, if we proceed:

• Build the proposed rear extension.
• Remove/rework the bad rear roof/extension area as part of that, rather than patching the existing poor geometry.
• Sort the upstairs layout properly, especially the roof intrusion into the rear/box room.
• Replace the old private drainage setup with a sewage treatment plant if feasible.
• Rewire, replumb, new heating, new kitchen/bathroom.
• Make the house warm and dry without wrecking the old fabric.

A practical (non traditional) builder suggested around £170k–180k for a proper refurb/extension to a decent spec. We are assuming the true all-in exposure could be higher once fees, contingencies, drainage, windows, and surprises are included.

The bit we are struggling with is prioritisation and valuation.

Some traditional experts are very focused on breathability, lime plaster, cement pointing, gypsum, black coatings and avoiding damp injection. A developer friend saw the survey and says some of it may be overblown: gypsum is not automatically a disaster, surface mould on rafters may just need better roof ventilation, cement pointing may not need wholesale repointing, and the big missing ticket item may actually be windows.

We are trying to find the sensible middle ground. We do not want a shiny new-build-style refurb, but we also do not want to spend money where something is not actually causing harm.

Specific questions:

1. How would you separate urgent structural/fabric risks from old-house imperfections that can be phased?
2. Would you treat gypsum plaster as a serious issue only where it is on damp solid external walls, or more generally?
3. How would we identify whether problematic backing plaster such as Carlite Bonding has been used?
4. If a circa-1900 cottage has later solid/concrete floors, how worried should we be about moisture being pushed into the walls, and how would you assess whether the floor is actually causing harm? Would you consider ripping the concrete out and going back to timber? Is concrete definitely not originalr in a 1900 property?
5. Is hard cement pointing on soft brick automatically worth raking out and repointing, or only where there is visible damage/moisture?
6. Is surface mould to rafters usually a major warning sign, or often just a ventilation issue?
7. Would you replace windows early, or only after deciding the full thermal/extension strategy?
8. Does it make sense to use a practical general builder for the main works, but have a heritage/traditional-building specialist guide the damp/plaster/breathability decisions?
9. How much weight would you put on the surveyor’s old-building concerns when deciding what to offer?
10. How would you price the risk when the rear extension/roof refactor will remove some of the worst existing defects anyway?

At the moment my instinct is:

• structural engineer for the ceiling/chimney/roof issue;
• drainage CCTV and treatment plant feasibility;
• proper window schedule;
• roof/ventilation assessment;
• no chemical damp injection unless very clearly justified;
• no wholesale lime/repointing works unless the diagnosis supports it;
• use the survey to negotiate hard, but not assume every flagged item is a disaster.

Does that sound sensible?

 

[phillc]

We have now had an initial survey/look-over done and are trying to make sense of it before deciding how far to proceed and what the property is really worth.

The house is clearly a project, but we are getting conflicting advice about how much of this is genuinely serious, how much is normal old-building stuff, and how much is “purist” versus practical.

Main findings/issues raised:

• The house needs substantial refurbishment, not just decoration.
• The rear of the house has an aborted/poor later extension, with awkward roof geometry and a compromised upstairs box-room/rear bedroom.
• One upstairs lath and plaster ceiling has collapsed, possibly linked to previous chimney alteration/removal or roof/structure issues.
• There are old private drainage/cesspit/septic arrangements. We would expect to replace this with a proper sewage treatment plant, subject to drainage survey/design.
• Some rainwater/drainage arrangements appear poor, with blocked gullies/manholes and water management issues at the rear.
• Some external ground levels/materials may be contributing to damp.
• There is black painted material (blackjack?) at the base of some external walls.
• Some pointing appears to be harder cement-type pointing on softer brick.
• The ground floors appear to be solid/concrete in at least some areas, possibly with a DPM. We are not sure if these are original, later replacements, or whether they may be affecting moisture movement in the walls.
• There is a mix of window types, including timber and PVC, and some single glazing despite the listing saying double glazed.
• Internally there are modern materials such as gypsum plaster in places, and the surveyor raised breathability/moisture concerns.
• There is some surface mould to rafters/roof areas, possibly a ventilation issue rather than structural timber decay.
• Heating, plumbing and electrics are likely to need major overhaul or replacement.

Our intended works, if we proceed:

• Build the proposed rear extension.
• Remove/rework the bad rear roof/extension area as part of that, rather than patching the existing poor geometry.
• Sort the upstairs layout properly, especially the roof intrusion into the rear/box room.
• Replace the old private drainage setup with a sewage treatment plant if feasible.
• Rewire, replumb, new heating, new kitchen/bathroom.
• Make the house warm and dry without wrecking the old fabric.

A practical (non traditional) builder suggested around £170k–180k for a proper refurb/extension to a decent spec. We are assuming the true all-in exposure could be higher once fees, contingencies, drainage, windows, and surprises are included.

The bit we are struggling with is prioritisation and valuation.

The house hasn't fallen down yet so likely won't in the 12 months after you buy it . If there are urgent things you need to do to make the house work for you (like build the extension) then crack on with that, otherwise there's always value in watching an old house go through the seasons. The priorities will then reveal themselves ...

Specific questions:

1. How would you separate urgent structural/fabric risks from old-house imperfections that can be phased?

As above, if you can wait for the house to tell you then do. I have a bias as I live in a cob property, so may be different to you. But, roof and roofline rainwater goods, together with drainage of rain captured is always at our near the top of any list. Then I'd look at ground levels and exterior wall coverings (especially external). It probably makes sense to address windows, a sa convenience, at the same time if you're rerendering.

Internal matters like concrete floors and gypsum plaster can generally come third - and can at least be left until the benefits of the above external work can be measured.

1. Would you treat gypsum plaster as a serious issue only where it is on damp solid external walls, or more generally?

As above. While not ideal, it may not be an issue. So, I wouldn't panic. Do the outside work first, see where any residual damp is after the house has had a year to dry out and you've ventilated/heated.

Yes, it's more likely to be a problem on a solid external wall than an internal one - but your house will tell you!

1. How would we identify whether problematic backing plaster such as Carlite Bonding has been used?

Unless your buyer is feeling generous about you hacking away prior to you buying, you can't.

1. If a circa-1900 cottage has later solid/concrete floors, how worried should we be about moisture being pushed into the walls, and how would you assess whether the floor is actually causing harm? Would you consider ripping the concrete out and going back to timber? Is concrete definitely not originalr in a 1900 property?

Solid floors in kitchen/scullery type areas would not be at all uncommon - our old house in Bristol had a 1910 concrete floor overlaid with 9inch clays. The Victorians had concrete (of sorts) and kitchens are pretty heavy duty environments for wood.

Once you've bought that place, get a piece of plastic and tape it securely to the floor. Wait a few days (preferably rainy ones). Lift it up. If the patch under the plastic is darker than the surround, the floor is breathable (to an extent).

Again, either way, live with it and don't panic. We now live in cob and have ground floor 1930s poured concrete. Walls are dry as a bone!

1. Is hard cement pointing on soft brick automatically worth raking out and repointing, or only where there is visible damage/moisture?

The main issue here will be damage to the bricks over time. It's never really good to have a harder mortar than the thing being mortared.

However, it is very unlikely to be urgent. Repointing over a set of warm summer evenings can also be very therapeutic, depending on your point of view. It's kind of easy work!

1. Is surface mould to rafters usually a major warning sign, or often just a ventilation issue?

If it's just white powder, don't worry. Ventilation. If you get a chance to go up there discreetly prod a few rafters with the end of your key. If they feel firm, great. If the key slides in, less great.

Worry if you see anything that looks mushroomy.

1. Would you replace windows early, or only after deciding the full thermal/extension strategy?

If you're having an extension I'd fix any immediate concerns with the roof and gutters; then do as much other stuff as you can stomach together with the extension (see pecking order above).

1. Does it make sense to use a practical general builder for the main works, but have a heritage/traditional-building specialist guide the damp/plaster/breathability decisions?

You just need a builder you can trust. Ultimately, as I think others have said above, you'll want to do some reading up on stuff (or asking here) so you can be informed and guide whoever you employ.

Be careful of "heritage builders" who are just builders but triple the price to pay for their use of the word "heritage". As others have said, it is far more important to ask them what they intend to do, and have a feel for what the right answer is.

1. How much weight would you put on the surveyor’s old-building concerns when deciding what to offer?

Only you can know this. Ultimately only you can decide whether you are going to buy the house (I bet you are as your questions suggest you are quite emotionally invested) and how much money it is worth to you.

All old houses come with problems, largely caused by a combination of period of neglect or the 20th century thinking it knew best how to repair them. It sort of comes with the territory.

Ultimately, don't panic. What is the house worth to you and how much would you be comfortable setting aside for fixes? Then, live within those means. You have time.

1. How would you price the risk when the rear extension/roof refactor will remove some of the worst existing defects anyway?

As above!

At the moment my instinct is:

• structural engineer for the ceiling/chimney/roof issue;
• drainage CCTV and treatment plant feasibility;
• proper window schedule;
• roof/ventilation assessment;
• no chemical damp injection unless very clearly justified;
• no wholesale lime/repointing works unless the diagnosis supports it;
• use the survey to negotiate hard, but not assume every flagged item is a disaster.

Does that sound sensible?

Yup.

 

[fernicarry]

If the windows are so far gone that they are allowing water into the fabric of the building I'd treat them with the same priority as the roof and rainwater goods.

As said, live with it for a while until you are really certain of where you need to put your money and who you want to give your money to.

And remember that the survey only tells you about problems that are in plain sight. Be prepared to find hidden problems once you start digging into it.

 

[topdog91]

Thanks so much for the ongoing support, it's really valuable and going in to our to-do lists and spreadsheet... I took a look at the EPC; now I can imagine that's a controversial topic around here especially with the *really* old buildings. Our view is that we would like to be pragmatic and even progressive and contribute to saving energy as much as possible without materially compromising the house construction's need to "breathe" for want of a better word. Our concern is that some of the EPC recommendations, especially internal wall insulation and floor insulation, may need careful thought with all the damp/breathability issues, later concrete floors, mixed plaster types, cement pointing in places, and external ground level/material concerns. We don't want to blindly follow EPC upgrades if they risk trapping moisture or damaging the old fabric.

Any early tips what to do and what to avoid based on the below? We haven't even decided how to heat the place yet; I would think gas / radiators for the existing house and underfloor for the extension. I know heat pumps exist but know zero about them as yet.

EPC summary:

Current EPC rating: E, score 45
Potential EPC rating: B, score 90
Total floor area: 67 m²

Element ratings:

Walls: Very poor
Reason: Solid brick walls, as built, no insulation assumed.

Roof: Average
Reason: Pitched roof with 100mm loft insulation.

Floor: N/A / assumed no insulation
Reason: Solid floor, no insulation assumed.

Windows: Poor
Reason: Partial double glazing.

Main heating: Good
Reason: Boiler and radiators, mains gas.

Main heating controls: Very poor
Reason: Programmer, room thermostat and TRVs are either absent/limited or assessed as poor.

Hot water: Average
Reason: From main heating system.

Lighting: Very good
Reason: Low-energy lighting.

Secondary heating: N/A
Reason: None recorded.

EPC recommendations:

1. Internal wall insulation
2. Floor insulation
3. Heating controls upgrade
4. Replace boiler with new condensing boiler
5. Solar water heating
6. Replace windows with new double-glazed units
7. Solar photovoltaic panels

 

[phillc]

There are lots of threads on here about internal wall insulation (look for "IWI" - I think someone pulled together a vade mecum of the forum's views a while back). I can't comment further on it - we're cob and, given how sensitive cob is to moisture movement, t'aint nothing going on my walls that is modern and fangled, no matter how good the marketing words about breathability are. (And, to be fair, cob is pretty good at insulating anyway).

To some extent with EPCs, you're buying an old house that was not deigned to modern energy sensitivities, so the question comes down to how much work you can tolerate. If you do decide to go for IWI, that will make your rooms a little smaller and might end up compromising things like original cornice. Is that acceptable to you?

Looking at your EPC list:

Walls: See above.

Roof: Rolling out some additional loft insulation (plenty of eco options like sheepswool or recycled plastics) is an easy win and non impactful. Why wouldn't you?

Floor: I'd not bother. If you have draughty suspended timber floors, add a rug.

Windows: If replacing the windows is too much, consider secondary glazing inside. You'll get a big chunk of the benefits without any of the hassle. Heavy curtains help too ...

Main heating: If you don't have a condensing boiler, that's worth looking at. There are also combination heatpump and boiler systems - heatpump provides most of your heat, boiler kicks in to help in high demand.

Heating controls: Adding TRVs to radiators is easy to do, so do it. General guidance is to leave at least one radiator non TRV so you don't end up with the boiler running but there being no radiators open to accept the hot water. If your heating does not have at least one thermostat (so, it just runs based on a boiler timer) that should also be changed. You can get wireless thermostats so this can be done without lots of cabling.

Hot water: Nothing to see here.

Lighting: Nothing to see here.

Secondary heating: Nothing to see here.

Priorities for me, based on "low hassle, instant win" would be loft insulation, heating controls and secondary glazing. Next would be boiler provision. Only after that, if the house is leaking cash keeping it warm, big projects like IWI.

 

[paulc]

Just to add my pennies worth. Based on my observations of gypsum plaster, it can "breath" a little. Possibly not as much as lime. However, if gypsum remains damp for any length of time, it turns to mush (something that lime doesn't do). So don't get too hung up on gypsum and start hacking it off where ever you see it.
Heating controls are well worth upgrading even if the boiler is a veritable antique. I used to have an old Baxi Bermuda back boiler - Very simple thing with no fancy electronics, and only two parts likely to fail (thermocouple and gas valve). Wired up a smart control system that allowed for different temperatures depending on the time of day & week. Straight away, I saw a 10% reduction in gas consumption. Next job was to fit a decent temperature sensor to the hot water tank so that I could shut the boiler down once the tank was up to temperature rather than on a fixed one hour boost. Although there were TRVs on most of the radiators, they contributed little to saving energy as far as I could tell.
The whole heating system got replaced a couple of years ago with a shiny new combi. Replumbed the system myself and fitted oversized radiators all round. This has enabled me to run at a reduced flow temperature which results in a higher efficiency (regularly get 92-94%). If I had waited a few more months, I could have got a heat pump for about the same money as I spent on a gas boiler. If you replace your heating system, I would strongly recommend pricing up a heat pump. If you stick with gas, keep the boiler within the envelope of the building rather than sticking it up in the loft or out in a garage. Two reasons for that - The PCBs do not have any conformal coatings and (generally) rely on a simple plastic case to protect it from damp (doesn't always work). Heat losses through the case can be 6% or more - Keep that heat within the living space, and it isn't wasted.
Rather than use the thermostat/timer that was supplied with the boiler, I kept the same smart control that I'd been using with the Baxi. Added a heat meter to the CH flow/return pipes so that I could record just how much energy was going in to heating the place. The data collected, helped to fine tune the system and also allows me to see what home improvements actually save money. Unfortunately, I didn't have it in place when I did loft insulation and replacement windows. That said, I had been logging temperatures and boiler run times, and new windows certainly reduced the amount of time the old boiler was running.

On to IWI. The upper half of this house is solid 9" walls, whilst the lower half is cavity (just 2" wide). Two bedrooms have had IWI fitted to date. one being done a little over a year ago. Looking at the data, I can't see any change in the rate of heat loss between rooms that have had IWI and the ones yet to be done. It certainly hasn't done anything to make any noticeable difference to gas consumption. However, there is no condensation or black mould on the insulated walls, but that could be down to better heating and more insulation in the loft (up to 400mm in some areas). As an energy saving measure, I'm not entirely convinced that it is worth the expense. Even with doing the work myself, I can't see that I'll see a return on the investment in my lifetime. That said, it should raise the EPC by a few points which could make it easier to sell the place. Oh, and I've got nice flat walls to decorate which is a bonus.

Priorities for me, based on "low hassle, instant win" would be loft insulation, heating controls and secondary glazing. Next would be boiler provision. Only after that, if the house is leaking cash keeping it warm, big projects like IWI.

I'd also add to the "low cost, big returns" list, plug all those nasty cold draughts. Well worth fitting an insulated loft hatch while you are topping up the loft insulation.
Oh, and worth fitting some form of home automation along with a few temperature & humidity sensors dotted around the place. As you make a change, you can look at the graphs to see if it was worthwhile - Does need a bit of computer knowledge and can be a slippery slope down a deep rabbit hole

 

[topdog91]

Will digest everything and thank you, but regarding the last point, I've spent my whole life around computers and 30 years with Linux; I'm very in to Home Assistant at the moment for my clients so perhaps I'll get a chance to use it at home!

 

[paulc]

I'm very in to Home Assistant at the moment for my clients so perhaps I'll get a chance to use it at home!

Oh dear. You're already on that slippery slope... Let's add a sensor or two to monitor electricity consumption. Ooo... Can use an ESP32 to talk to the boiler... Hrmmm... Smart light switches and an automation, don't need cables going from the hall to landing... Someone keeps leaving the pantry light on. Run an automation to turn it off when the kitchen light is turned off.
Now just need an LCD somewhere to display all this data.. maybe run a modbus network round the house while the place is being rewired... Ah, a heat meter on ebay, and its only £20...
Yup, some of us are still digging that hole

 

[topdog91]

Oh dear. You're already on that slippery slope... Let's add a sensor or two to monitor electricity consumption. Ooo... Can use an ESP32 to talk to the boiler... Hrmmm... Smart light switches and an automation, don't need cables going from the hall to landing... Someone keeps leaving the pantry light on. Run an automation to turn it off when the kitchen light is turned off.
Now just need an LCD somewhere to display all this data.. maybe run a modbus network round the house while the place is being rewired... Ah, a heat meter on ebay, and its only £20...
Yup, some of us are still digging that hole

Bring it on! I'm new to HA; I kind of stumbled on it by "accident" - been aware of it for a long time and most of my work is in software engineering. Then a mate was complaining about his Control4 installation (and price fixing) and the rest was history.

Honestly, I hadn't even considered that use case of cable-less lighting. Then again, whilst everything is bare (and having seen the survey results I can see that happening), I would probably cable up; belt and braces etc.

Thanks for the Modbus tip; another useful buzzword to dig deep on!

 

[paulc]

Thanks for the Modbus tip; another useful buzzword to dig deep on!

I was just running through some of the stuff I've done. Also had to run an MBUS cable down to the heat meter. Then an assortment of ESP32 devices to do "stuff". One of my favourites is a 4" display (with built in relays) that sits in a 35mm back box. Acts as a virtual thermostat, displays short range weather forecast, interface for an EV charger, clock, and light switches. Contemplating adding a HA script so that I can display realtime energy consumption graphs. Currently running openHASP on it, but giving some thought to using Tasmota and Berry. So many toys, so little time.

Oh. one more tip - Run a neutral wire to all the light switch back boxes and safely terminate them. When you start installing smart switches, you'll be glad you did. Yes, you can get smart switches that don't need a neutral, but many reviews say you get flickering from bulbs along with other "issues". Not seen any of the 4" displays running without a neutral either. There are also kinetic switches, but they quickly end up being very expensive once you've purchased the receiver modules too (and not all work out of the box with HA).