Devon Cobb cottage

[alihBC]

Hi there any ideas greatly received pls
Bought a cottage / had no idea about Cobb /renders/ nor did the level 3 survey / surveyor apparently but now I understand the situation and how we need to have the render taken off and lime plaster inside and outside / breathable paints etc. one day …..
However today s fresh hell was : I looked under the carpet in the lounge to see if it was damp as the edges of the walls were.
Hey presto ! Damp chip board throughout the lounge /diner. Have been told to take the carpet/underlay out - let the areas dry.
Moving forward how do u fix the problem? There is a blue plastic membrane under the chip board ?!!
Do you put limecement down? Under floor heating? Is this particularly costly? Any advise greatly received
Many thanks

 

[aockenden]

Is it a suspended timber floor or solid floor? I think I know the answer but want to hear it from you. What are all the layers of the flooring system, moving from the carpet all the way down?

 

[alihBC]

Thank u for your reply
Sorry I don t know - it is carpet/underlay/wooden sheets of chip board/ when I tap it it sounds hollow/blue plastic around the edges
Does this answer your question pls?

 

[aockenden]

I advise you to learn more about your house. Deeply investigate how it’s been built. What’s beneath the chip board? What’s beneath the blue plastic? Knowing that you’ve either got a suspended timber floor or a solid floor is a really fundamental piece of information that you should know.

The most successful home owners (especially of old homes) know every inch of their house’s fabric, top to bottom. How can you craft a solution to the problem if you don’t understand the existing state of things?

 

[alihBC]

True say
I shall investigate further. I never realised what we were buying to be honest - only now am i understanding the magnitude of this ancient cottage. I already mentioned - I thought a level 3 survey would guide me to areas of concern. It did not.
I was not informed by the problems of render on Cobb walls/ damp coming up from the floor but I am learning thick and fast
Thank u for your reply

 

[Lacan07]

Hi there any ideas greatly received pls
Bought a cottage / had no idea about Cobb /renders/ nor did the level 3 survey / surveyor apparently but now I understand the situation and how we need to have the render taken off and lime plaster inside and outside / breathable paints etc. one day …..
However today s fresh hell was : I looked under the carpet in the lounge to see if it was damp as the edges of the walls were.
Hey presto ! Damp chip board throughout the lounge /diner. Have been told to take the carpet/underlay out - let the areas dry.
Moving forward how do u fix the problem? There is a blue plastic membrane under the chip board ?!!
Do you put limecement down? Under floor heating? Is this particularly costly? Any advise greatly received
Many thanks

A few photos would help. I'm guessing you've got a concrete floor. Any sign of damp on the surrounding walls?

Surveyors know zilch about older properties. You'll get differing opinions on here about how to deal with floors and there's many options to choose. For example I'm not a huge fan of insulating a suspended floor.

 

[WaterMason]

Like aockenden said, it would be good to know what’s going on underneath. It’s sounds like the suspended floor with damp proof membrane underneath, could have been an attempt to solve an older problem.
I am a stonemason and natural builder, I’ve had a lot of dealings with cob buildings and damp floors.
As you’ve identified, you are looking to make your walls breathable, I’d take a similar approach to your floor. Expanded glass foam is a brilliant sub floor material. It’s insulating, inert and non capillary so neither rots, nor allows moisture to rise though it. Mike Wye is a great starting point for information on potential floor build ups https://www.mikewye.co.uk/wp-content/uploads/2014/09/Glasscrete-Installation-Guide-V1.pdf
Any way, that’s something to think about.

 

[alihBC]

Thank u all for your comments. I believe it is a suspended floor as it’s hollow underneath - I will take it up when I have a minute
Interesting u say glass foam and not limecrete I ve not heard of that one (tbh I’m learning everyday)this forum is brilliant - well the people on it are.
Yes there is damp on the walls where the floor meets the wall. Yes I did have a damp remedial injection by a contractor and yes I am trying to take the surveyor and contractor to court.
Will get onto Mike Wye
Thank u

 

[alihBC]

Extra photos showing the wet floor and the cottage

 

[aockenden]

View attachment 12509

That looks like a row of terraced houses. Is it all actually 1 property or do you own just a single section? If you only own a single section, which section do you own? Can you circle it on the pic?

The reason I ask is that for most of that structure I would be shocked to learn it was made of cob based on the external appearance. I also saw your other thread where the only exposed walls you showed were red-brick. Have you actually found any Cob anywhere in your house?

 

[Stevers]

Yes it's all too straight and square, and looks like it's had a lot of work done on it recently.

 

[LadyArowana]

The fact that hard paving goes right up to the house and there’s some plants growing by the pipe ( drain? ) will most likely be contributing to the issues. It may even be that over time ground levels outside have increased with that paved area covering over vents designed to keep air flow below the floor. There’s lots of infos on the site about French drains being installed to help resolve these sorts of issues

 

[alihBC]

Thank u for your replies
Yes it is all one house now but was once a barn and a dwelling or maybe 2. Now it is one 5 bed cottage
The render was painted 4 years ago and some Keim paint was painted on the render. A new surveyor has found cob in the roof / gable ends.
I shall look into French drains.
Thank u for the tip
I have also phoned Mike Wye and understand the GSL / back to soik/ the glass pebbles/then limecrete/ then the chosen floor : wood/ manufactured flooring or battens for carpet ?
Which flooring do u think would be most appropriate?
The surveyor mentions under floor heating - I personally am hesitant to have underfloor heating installed
Many thanks

 

[alihBC]

 

[alihBC]

Hi there
Pls help us if you feel generous.
Took up the carpet / underlay as felt wet to touch- saw the chip board / made a hole saw polystyrene/ the blue dpc liner then sand and then we thought we could see soil/mud underneath BUT it feels solid like a stone /cement
Moreover it is all bone dry?!?
Why is the woodchip damp on the top pls?
What is the stone underneath the blue plastic? Is it cement ?
As u can see I am a novice
Any knowledge greatly received
Many thanks

 

[aockenden]

Hi there
Pls help us if you feel generous.
Took up the carpet / underlay as felt wet to touch- saw the chip board / made a hole saw polystyrene/ the blue dpc liner then sand and then we thought we could see soil/mud underneath BUT it feels solid like a stone /cement
Moreover it is all bone dry?!?
Why is the woodchip damp on the top pls?
What is the stone underneath the blue plastic? Is it cement ?
As u can see I am a novice
Any knowledge greatly received
Many thanks

Good for you doing a deeper investigation. Unfortunately I think there’s no telling what’s under the blue plastic until you remove enough of the covering materials to completely identify it. Or maybe you could take some kind of sample and get it tested, idk. But given the evidence you’ve provided so far, it could definitely go either way: either a modern poured-in cement slab or possibly original flagstones.

Either way, the fact that you hit something hard and rocklike immediately beneath the blue plastic suggests that you’ve got a solid floor not a suspended timber floor. Do you have any ventilation bricks / grates / grills on the outside of your house near the bottom of the walls near this area? If not, that also would suggest a solid floor not suspended (although this is still not a truly foolproof metric as bodge-it builders routinely seal-up ventilation bricks).

 

[Stevers]

Are you sure that the carpet etc. didn't feel 'cold' rather than 'wet', since the DPM should protect the chipboard even if it drives moisture into the walls. On the other hand, I'm always concerned with insulation as to where the dewpoint might be - in this case my understanding is that the DPM (as a vapour barrier) would be the wrong side of that expanded polystyrene, and it's not impossible that there might be condensation occuring inside that insulation, and being drawn into the chipboard. Once something is damp, it's cold, and it becomes something of a viscious circle that needs breaking. One other possibility I suppose is that the DPM is not as continuous as it could be.

To my mind if you're going to dig out for what will prove to be an expensive limecrete/glass whotsit floor, why not cost out what I'm sure would be a less expensive suspended timber floor and vent the resulting void. That utterly conventional approach should help the walls too unless you have very shallow foundations.

 

[alihBC]

Thank you aockendon
You ll be proud of me one day
I’ve even visited a wonderful Cobb house this weekend

 

[alihBC]

That is v interesting Stevers….. there is now talk of the dew point from someone else - oh gosh it s not easy
Should it go:
Concrete
Sand
DPM
Polystyrene

Or
Concrete
Sand
Polystyrene
DPM

Frankly we need the least expensive option.

There are no vents /grills outside /exterior walls

I believe it is a solid floor but my neighbour has a vents in her walls and she believes a suspended floor.

I appreciate the vents in the walls will help with ventllaton

Is this more of an old fashioned approach pls? It’s a cob house I don t have foundations - it s built on mud

The cob house I saw had put the glass beads /lime only around the perimeter and dug out french drains to the exterior.

Last question:
If I have a suspended floor can I put wood on that ?

We have a dog and natural jute carpet isn t very appealing

Any thoughts pls?

 

[Stevers]

You really need to work out what the problem is that you're trying to solve before thinking about how to fix it.

By suspended floor, I meant a timber floor on joists and sleeper walls. You need to invest in some building construction books to get a better idea of what you're dealing with (and I don't think it's 'cobb'), other options for how it could be, and to understand the enormity and chance of success or otherwise of any scheme of work suggested to you. This sort of stuff gets very expensive very quickly without a really good plan!