Back to brick - preparing our window openings for new Viking windows

Hi folks, we’ve just had lovely new Viking triple timber windows installed.

I’m a bit behind documenting it all, but here’s a blog post about taking the window openings back to brick - and the horrors we found and fixed along the way :grimacing:

Hope it’s interesting & useful to someone.

Very interesting. Thank you.

I had new triple glazing fitted before I discovered high performance windows. Actually it is worse than that. I ordered the windows, paid the hefty deposit and then discovered high performance windows.:man_facepalming:

After they were fitted I could clearly hear the outside world. I removed the trim and found much the same as you. I didn’t need to go to quite the same lengths. I cut back the reveals. Foamed the gaps, trimmed flat, painted with Blowerproof, including all exposed brick & block, and then relined the reveals. Much better. Some of the cills I am leaving until we decorate the rooms.

Hi @paulf,

It is interesting and definitely useful (sorry to hear about the injury!).

Having documented examples of tricky jobs like this goes along way to demonstrating that they can be done to the same if not higher standard than the trades (who, in fairness to them, can be time and cash pressured, hence being known to sometimes rush and not produce the best results).

Thanks for sharing.

@Tim_Gilbert I owe you one for a previous post about your windows - it tipped me off that it was even possible to install them badly, so I knew I needed to learn more before talking to installers. I was able to attend an “ask a Passivhaus architect” session, quiz a Passivhaus builder and of course pester People Powered Retrofit until I felt I sufficiently understood how they should be installed.

In the next blog post I’ll expand on the detail of how the install was done, what tapes, foams and method etc.

In the meantime I’m working out how best to insulate these reveals. Depending on the window I’ve got 30-50mm total to play with. I’ve been pointed towards straightforward insulated plasterboard (expanded polystyrene + 9.5mm plasterboard). I don’t love buying new petroleum-based materials to be honest. But it is readily available and familiar to the plasterer who’s going to finish up the “messy bit” at the end, which is something.

Any thoughts would be welcome!

Cheers @john.d. I do enjoy learning and doing stuff myself which really helps. I’ve made plenty of cock ups too, but that’s how we learn :smiley:

Regarding tradespeople, as you mention, the time-and-cash pressure really is a thing. The price-comparison-website mindset has trained us into going with the cheapest and leaving no margin for the tradesperson to go the extra mile.

It’s a balance though: on the flip-side, a neighbour of mine recently told me they’d been quoted £11K for solar panels … the same capacity that I paid around £4K for, 8 years ago.

Why’s it so hard for to get good quality at a fair price?!

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Thoughts I can give, answers I can’t. There are too many variables.

One of the first things to consider is whether you are in your “forever home” or not. It shouldn’t really make a difference as you hopefully want to do what is best, not only for yourself but also your successors. The big difference is that if you and/or your family continue to live in the house you can make future choices that maintain the breathability of vapour open finishes, whilst a new purchaser might slap on vinyl wallpaper or plastic paint and instantly ruin a part of your work. If you use a natural fibre construction it could be all your work, not just part of it.

Generally, totally impermeable window reveals shouldn’t be a serious issue if the rest of the wall is breathing, so you could take a non pervious route. What you can’t do is mix and match. That does assume that the wall is weather proof and you have adequate internal ventilation to stop condensation forming on the wall surface, including the reveals.

If you are fixing the insulation and board yourself and just getting a plasterer to tidy up then you could use quite a range of materials. If however you are allocating the whole job to someone else you will get a quicker and maybe neater job sticking to materials that your plasterer is already familiar with. However, for a price, you should be able to specify whatever you want. A plaster could quote you for fitting egg boxes to the reveals and making good but he would charge a fortune to cover unknown costs and risks.

Note that generally the side edges of reveals are hidden by curtains, so you don’t really need a first class finish. The top edges are more problematic if you can’t hide them with curtain rods or pelmets.

I am away from home for half term so don’t have my reference works available. That sounds amazingly academic, but it isn’t. I have several years of back numbers of Passive House + magazine. I’ll try to remember to look up a few useful products. That gives you time to think about the desired breathability and report back.

Unfortunately the purchaser needs to assume that “install badly” is the default.

This is at least partly because there is no training required to become a window installer. It is only the extent of “badly” that is the variable.

I used compressed wood fibre board (With our 23ml UdiIN 2cm board we were expecting it to achieve a U value of 2.1, but when it was measured the U value was 1.4. So it was performing about 30 per cent better than we actually expected. The 23ml board actually reduced the heat loss through the wall by about two thirds. ) Back to earth. I fitted these myself cut and glued to the brick reveals and got the plasterer in to cover up. It is also possible to use Bauwer perlite.
Skirting boards also hide horrors. I used an IR camera to identify draughts and large cold areas that hide large holes!

Funnily enough, or perhaps I should say “sadly”, I was reading today that some builders are setting themselves up as airtightness specialists and were sealing the gap between skirting and floor as a permanent solution. In reality it only pushes the symptoms along to the next week spot.

Ah, found it: See the bottom of this,

I’m not sure what’s necessary for this house. Some factors:

  • It’s 1980s brick, cavity, block.
  • Existing plaster is “normal” wet plaster or gypsum plasterboard
  • It has great ventilation now we’ve installed it
  • The walls are fairly well protected by large overhangs from the roof.
  • The airtightness tape I’ll be sticking to is vapour-open.

I’m going to do most of the work myself. My plan was to get the plasterer to do the final edge beading and messy, skilled bit.

I take your point about reveals being hidden behind curtains etc. For us, some are, some aren’t. I’d prefer a pro to do that bit.

“What’s necessary” can be interpreted two ways, what is best for the house or what can I get away with. The average tradesman opts for the latter. I presume you mean the former.

If you can, opt for permeable fabric throughout the building envelope. If there is no risk of damp in the walls you have a free choice of natural fibres and permeable boards. Plaster board is permeable but tends to be too hygroscopic to be a good choice for breathability. There are calcium silicate boards available at a price. They are somewhat reminiscent of cement board and tolerate some damp. Alternately a layer of a higher density wood fibre board can give a good finish with a thin plaster skim coat.

If the reveals are completely unlined when fitting the window you can revise the plane that you fit them into. Try to fit into the insulation layer to minimise thermal bridging. Alternately if the next project is EWI you can fit on the outer edge of the wall, so that the EWI can abut the frame and overlap a little. You will have significant thermal bridging until the EWI is in place.