Brickwork!

[GeorgianProblem]

Hi,

I'm after some advice if possible, I have just taken off some concrete render on a Georgian property and it has revealed badly damaged brickwork. I can't believe the difference to the bricks when taking off the old lime plaster v the old concrete render. So much concrete in this property.

Would this be a case of raking out, repointing with NHL - i'm unsure if 3.5 or 2, this is an internal wall. Following that do I apply the insulating render to build up to roughly smooth with the rest of the brickwork and then start the insulating render coats?

Are there any other things to consider, looking to make the property as breathable as possible. i think i will use insulating render instead of fibre boards to try and reduce the amount of room space that is lost.

What is the best way to conceal pipes and wires in the render if anyone has any experience/images that would be hugely appreciated.

Thanks very much,
Ollie

 

[paulc]

What is the best way to conceal pipes and wires in the render if anyone has any experience/images that would be hugely appreciated.

For repointing internally, you could mix some lime putty and sand - As long as it is kept in a reasonably air tight tub with a splash of water on top, it will remain usable for years.

As for pipes & cables - 20mm plastic conduit for everything. Conduit will allow you to pull new cables through should you ever need to. Tip: Use 35mm deep back boxes, even for light switches. And if you run a neutral to each light switch back box (suitably terminated), you can install smart switches should you ever feel the need.
15mm copper pipe will slide down inside 20mm plastic conduit which will protect it from any corrosive effects of plaster. But you need to ensure that there are no buried joints. Where the pipes come out of the wall, use a 35mm single back box at that point to make it easier to connect to the outside. Oh, and put some steel capping over the pipes to stop someone banging a nail through (I used some strips of stainless steel with mine). Some would say use plastic pipes for any buried plumbing, but quite frankly, I find the fitting to be piggin' ugly and best left with the plumbing merchant.
Oh, and if you are replumbing the heating system, it is well worth designing the system to use a 50°C (or lower) flow temperature. This may well mean larger radiators and a lot more 22/28mm pipe. This extra work will mean that you can run at lower temperatures which will push up the efficiency of any condensing boiler as well as reducing the risk of burns from roasting hot radiators. Longer term, it also puts you in a better position should you ever need to install a heat pump.

 

[Cubist]

If your ultimate aim is to plaster those internal walls then raking out the old mortar is, in my opinion, largely pointless. However, it would be worthwhile repairing the more significant holes and crevices before applying a plaster base/render coat before a skim coat to produce the final finish. Other members here are more competent than I concerning the lime products and most appropriate.

Regarding coverings for the cables. Personally I see little advantage to using plastic conduits as these afford very little greater protection than the heavy plastic coating of outer insulation of the cables themselves and certainly none at all from 'a clown with a drill'. The only exception being where two or more cables must be joined and in such appropriate junction boxes should always be used.

As to plumbing pipework. The fittings for plastic pipes tend to be bulky and ugly and if the pipes themselves are not properly supported the whole lot can collapse like a pile of spaghetti. For copper pipes any section that must run through a wall should be wrapped in electrical insulation tape to prevent direct contact with mortars or plaster. Exposed runs of copper pipework should be left exposed if at all possible or preferred. If they must be covered for any reason then it is best to 'box' the pipes in while making sure that the coverings can be quickly and easily removed to allow rapid inspection and repair in the event of a leak. This is particularly important if the pipes are old as 'pin hole' leaks can occur at any time and in any location. New copper pipework should be pressure tested for the much same reason due to faults during manufacture or damage in transit or storage. Never allow copper to come into and remain in contact with steel - in the presence of damp, galvanic corrosion will be induced to corrode heavily corrode the steel,

 

[larry]

Sorry if I've missed something blindingly obvious, but why are you planning to use insulating plaster for an internal wall?

 

[larry]

If it is internal then as above would just repair any deeper holes or issues with a lime mortar mix (I'd use NHL as I've got a bag of it in my shed already, but a lime putty mortar will be more flexible) then whack some lime plaster on top. Here though, if it's internal, the breathability is unimportant, but the flexibility (of lime cf. Cement) likely is.
I'd also suggest as cubist does running pipes on the outside and not burying them but I'd put the cables in the wall in conduit. You can also get the steel capping stuff which you might want to avoid on an external wall (steel = cold = condensation risk) but on an internal wall would be fine. Be careful to respect the rules of cable running though so the next owner knows where to avoid if drilling holes). I think some form of mechanical protection of the cable is necessary in the regs even if as Cubist says it provides almost nil protection in reality (steel capping maybe a tiny bit better). Take photos of the cable runs before plastering over!

Can't tell what floor covering is from pics but other options is to run plastic pipes under floor (remember pipe insulation) and then bring copper up to the rads. If you buy the bendy plastic pipe you can sometimes almost do without elbows etc. I always go for JG speedfit but HEP is also well regarded and both are like plumbing Lego.

 

[Cubist]

Just in case @Zebra comes along to give me a shock with a HT correction.️

Domestic electrical cable runs in the UK must follow BS 7671 (18th Edition) regulations to ensure safety and prevent damage, particularly by using designated "safe zones" for hidden cables. Cables must be buried at least 50m deep or, if shallower, protected by a 30mA RCD and running horizontally or vertically from accessories or within 150mm of corners/ceilings, also with metal conduit/coverings for the cable. Then theres the Part P compliance requirement.

 

[fernicarry]

at least 50m deep

50mm I think you mean!

If less than that then either mechanical protection (capping, steel conduit) or RCD. RCD generally being the easier option.

Plastic conduit is still helpful if you think you might ever need to alter the cabling as you don't need to tear open the wall to get at it. You can also get away with a little bit less derating if using conduit inside insulation as compared to a cable completely surrounded by insulation. Although I don't think a small depth of insulating plaster would really count as insulation for these purposes, they're thinking more of loft insulation type thicknesses.