Dry Lining

GreeBo

hey, just recenlty moved into my new house, 3 bed semi.
Before we start on all the redecorating we are considering drylining the exterior walls.
Is this crazy or worth it?
Right now it appears to be cavity block with fiberglass insulation then the studs/plasterboard.
the fiberglass seems to be pretty crappy (house is 15 years old) but I dont want to go to all the hassle of ripping it all down if its not going to gain me much...
Would I be better off just replacing the insulation with a better modern version (Kingspan?)
Ive heard rumours that houses will be getting an energy efficiency rating in the next 5 years or so, so Id prefer to do this now rather than after we have it done up.
cheers!

patrido

I was just reading about this half an hour ago

Kingspan TW56 seems perfect if you go the drylining route. It's a 12.5mm plasterboard with insulation attached ranging from 25mm to about 80mm. Don't know how much it costs yet, though I'm sure it aint cheap. However, putting money into insulation is almost always money well spent.

I can recommend contacting Kingspan's tech support department - they've always been very helpful with any query I've had. Their contact details are on the back of the pdf linked below. They should tell you what thickness you'd need to achieve certain u values, etc.

http://www.insulation.kingspan.com/ireland/tw56.htm
http://www.insulation.kingspan.com/newdiv/pdf/tw56.pdf

Btw, xtratherm are very good too, and probably do a similar product.
http://www.xtratherm.com/

GreeBo

cool!
so what actually is drylining, is it just plasterboard with an insulated backing?
do you still put instulation between the battons?
Im concerned about the extra thickness when it comes to areas like door frames, windows, sills etc?

patrido

GreeBo wrote:

cool!
so what actually is drylining, is it just plasterboard with an insulated backing?
do you still put instulation between the battons?
Im concerned about the extra thickness when it comes to areas like door frames, windows, sills etc?

As far as I know, drylining is a combination of insulation, plasterboard and moisture barrier.

The requirement for the amount of insulation you need, really depends on what u-value you are trying to achieve. As you are not getting planning permission for anything, there is no requirement for you to use any particular value, but if you were doing a new build, you would need 0.27 whatsits. Renovations might have a slightly lesser requirement.

The tw56 document has tables detailing what thickness of insulation you need depending on the type of wall you have and the u value you need to achieve. If you consult this it will say that you need xx mm insulation to get 0.27 for your wall type.

If you then consult Kingpsan tech support, or an architect/enginner, they should be able to tell you how much you can reduce that thickness by, if you put insulation between the battens, or if you keep your existing insulation.

rooferPete

Hi GreeBo,

Patrido has given some very good advice, insulation and natural daylight are probably the only two items in construction that actually pay back more than they cost and most last the life of the building.

The new rules are that all houses being renovated or restored are supposed to have the insulation upgraded as the work progresses, but not all are insulated because of the initial outlay.

You are supposed to leave an air space behind the insulation if using laths, also the laths are supposed to be short of the top and bottom to allow the air to circulate.

.

gregos

Hi GreeBo.

You raise a very interesting question here, and there are many factors to take into account.

Regarding effectiveness, this method of insulation ensures that you have the thermal mass of the walls available within the building to smooth out fluctuations in temperature, like a big radiator, and even perhaps to capture some energy by solar gain. Very good. Also, it's a far less invasive method of insulation than internal dry-lining. However, it's possible that you might need planning permission. Also, if your house is semi-detached, it might look a bit strange at the boundary with your neighbour; ideally, you'd want to do both houses together. Because it extends the thickness of the walls outwards, it can cause issues with the eaves, soffit and fascia. The external reveals will also need to be re-done.

On the face of it, the cost of doing this work seems high, compared to dry lining. However, there are factors involved in dry lining that people sometimes overlook. For one thing, you'll lose a significant amount of floor area. I personally wouldn't bother dry-lining without including at least 60mm of Kingspan insulation or similar. Not polystyrene, by the way. That means losing at least three inches off the width and length of each room. Furthermore, you'll have to relocate all skirtings, sockets,light switches and radiators on external walls. The same thing applies to coving, if you have it. You'll have to re-make and plaster all internal reveals, replace all window boards, and redecorate throughout. You'll also have to either skim or tape and fill all the new plasterboard slabs. If you wanted to be absolutely thorough, you'd need to remove the kitchen units, but you probably wouldn't want to do that. Even when you've done all this, there will be gaps in your insulation where the internal walls and first floor meet the walls and you can't insulate. None of these are factors with external insulation.

Incidentally, there's really no need for battens. Plastic mushroom fixings are very effective and for the most part eliminate the requirement for battens. Again, on a personal note, I just don't know how builders around Dublin get away with cavity-block walls.

By the way, are you sure your house isn't timber-frame?

GreeBo

argh!
I dont think I want to go down the road of external insulation, especially since the finish on the interior is bad enough to warrant a re-skim anyways...
so I guess if I remove the battens then I will be able to use that thickness of drylining without interfering too much with the existing reveals etc?
Yeah, its deffo not timberframe...
Will all this be worth is btw?
Do you think its a DIY job (except for the skim) or would it be better (quicker!) to get someone in?
Thx for all the advice

gregos

G'wan g'wan g'wan. Do it yourself. You have to start somewhere. And don't forget, you can always come back with more questions if things are getting on top of you. As regards being worth it, you'll notice an immediate improvement. By the way, is your attic properly insulated? That will bring instant results, and I'm quite serious here when I advise you to have 300mm of fibreglass or equivalent.

GreeBo

its not the effort its the 3 months later and I still have 3 walls to do problem!!

Attic is insulated but not to that degree, has about 4-6 inches or fiberglass and then is partly floored with chipboard.

gregos

If you want keep a bit of the attic for Christmas trees, insulate between the joists in that area with Kingspan. Then cover the rest of the attic in fibreglass. An extra 6 inches will make the kind of difference you won't believe. Regarding the walls, you don't have to do all the rooms at once. Finish one room and move on to the next. It will be much quicker than you think, and you'll acquire all sorts of new skills. Don't be put off by the fear of making mistakes. You'll have fun and you'll have a laugh at how much money you're saving. This is not rocket science - in fact, I'm not at all certain that rocket scientists know much about dry lining.

GreeBo

thinking about this again and talking to a few more people Im not sure is it worth it
Its not going to be my final house, 5-7 years max
I'd rather get double glazing and a "proper" front door instead
Things like windows/doors and the stairs sound like a royal pain in the ass to be messing with.
Obvioulsy you can never really have too much insulation, but Im guessing 99% of the houses in my estate have exactly the same levels as mine, so I dont think that will be an issue when it comes to selling.
I wanna keep the attic mainly floored, but I can certainly "fill in" under the boards.

I reckon I will be better off, both as an owner and a potential seller with new windows and doors
opinions?

Kaisr Sose

Hope it's ok todrag up and old thread. Hopefully someone has been in the same boat since

I have a similar dilemma to the OP with a late 1990s semi with I assume uninsulated cavity wall, minimal fibreglass insulation and 9.5mm plasterboard and double glazing. The attic insulated between joists and I will add another 150mm at 90⁰ across the joists

This was a rental house and I will be living in it for the next18 months or so. It requires a full decoration inside, including new kitchen, new boiler. I am wondering if it's worth fitting internal insulation. Pumped cavity would anothe option but I am concerned that it can create damp/mould problems if there is cold bridging and that sometimes the insulation does not fill the complete cavity due to building debris etc in the cavity .

By removing existing drylining, with I guess 2" battens and fitting 50 or 60mm PIR insulated plaster board give a significant improvement in u-value or would it need to be 100mm to be worth the work?

whizbang

'I assume uninsulated cavity wall' - No point in making any plans until you know exactly. Treatment differs with different build types.

Also are you aiming for better comfort or better resale value(BER Rating)?

Bargain_Hound

My 3 Bed semi is built with cavity blocks. I'm very eager to begin this process to all external wall facing bedrooms upstairs as two of the front bedrooms are quite cold. I would love to attach new 72mm insulated plasterboards directly to block walls by going full dot and dab (Or adhesive) creating unvented spaces behind the PIR Plasterboards, including a proper moister barrier installed on warmside (or even if taping the joints is enough, go with that as the boards have vapour control integrated). I believe the need for ventilation behind is negated if no moisture is transferring to cold the walls, and the added benefit of saving on an extra few MM per room not requiring battons, which is a lot when it comes to 2 small bedrooms. Going by the advice that .27 u-value required under building regs as minimum, a product such as Xtratherm (below) would meet these requirements based on the stated thermal performance

It achieves .26 installed on 215mm Hollow Block (External Render). However, I really believe this performance depends highly on the installation quality.

https://tjomahony.ie/72-5mm-x-2-438m-x-1-2m-insulated-pir-plasterboard-8-x4-t-liner-128028.html

My house is very poorly constructed and currently is constructed with battons and 37mm insulated PIR plasterboard (25mm insulation). Every wall has drafts transferring up and down behind them and it penetrates every gap in the house/floorboard/skirting creating very cold rooms, particularly on windy days. I would love to strip each room one by one and create air-tight as much as possible and be more in control of ventilation in each room via a vent if required.

A friend recently spent quite a long time warmboaring each room one by one and swears its made a huge difference to comfort levels in those rooms.

DublinDilbert

https://www.boards.ie/discussion/comment/123882381#Comment_123882381

Don't dot and dab the boards, use the sticky foam and some mechanical fixings, really good job. Put some foam inside the fixings too and attach thermal caps on them before plastering. Yes it is very much worth it, also peel back the inner reveals around the windows, use air tightness tape on the window and insulate the reveals with a thin board.

Kaisr Sose

https://www.boards.ie/discussion/comment/123881226#Comment_123881226

Its a good question on what I want to achieve. I would prefer a warmer house if I am living there, but whether I get an uplift in the eventual sales price is an unnknown. A better BER should , and was supposed to impact value, but I don't know if this is the case in practice.

What is the best way to determine if there is insulation in the cavity ? I have an inspection camera and could drill a hole and check. Before doing that I will check the kitchen extractor wall hole with the camera to check for insulation.

Black_Knight

https://www.boards.ie/discussion/comment/123898741#Comment_123898741

Kitchen extractor hole is a good idea. Meter box is another place to try check. Or if your changing any windows and doors you can check there too. If you go the pumped cavity route, be sure to change any windows/doors first.