Dry Lining

championc

I have a Semi and I'm re-decorating the hall and landing now. My house was built in the early 70's and is made of cavity block so I cannot insulate within the wall and so the hall / landing wall is currently un-insulated. With energy prices now looking like shooting upwards by 20%, I am seriously thinking about dry lining the wall.

If I DIY installed plasterboard with 25mm of insulation, and if heat loss would be currently at 35%, what would the aproximate new loss value be ?

Assuming it's worth doing, can I just get pre-insulated plasterboard sheets and attach then directly to the current wall with mushroom fittings or do I need something between the insulation and the original wall ?


C

Al Capwned

If your wall is constructed using cavity blocks, then it's next to impossible to get a proper fixing with mushroom fittings.

Either use bonding compound to stick the slabs to the external walls, or securely fix battens to the wall and screw the boards to the battens.

Al

TopTec

Presumably these are outside walls you want to insulate Champion?

TT

championc

alproctor wrote: »

If your wall is constructed using cavity blocks, then it's next to impossible to get a proper fixing with mushroom fittings.

Either use bonding compound to stick the slabs to the external walls, or securely fix battens to the wall and screw the boards to the battens.

Al

I'm all set to do the job this weekend. I see the "proper" method is to chuck blobs of bonding compound onto the wall and then lash up the boards. However, I can't see myself being too brilliant and sticking the blobs so I was wondering could I use a notched trowel which has an edge like _n_n_n_n_n_ and just spread over the wall ? I would plan to use some mushroom fixings anyway too.

TopTec

NNNNNNNNNOOOOOOOOOOOOOOOOOOOOOOOOOOOO!!!!!

If you are putting up 8 x 4 sheets, butter the back of the boards (the grey side). The blobs should stand around an inch out at least and the edges should have a blob every few inches.

Offer the board against the wall and use a long heavy piece of timber and use it to knock the board flat to the wall. Then the next and so on. The consistency of the adhesive should be like very stiff porridge.

Put your tile trowel away - not needed.:D

Corkey123

Unless you've done this before do not go down the blobbing route. It is a difficult job and results are often less than satisfactory.

I don't see why you cannot use mushroom fitting on cavity blocks. In fact I'd suggest they are potentially best suit to cavity blocks - I have used hundreds on cavities without any issues Just don't let anyone convince you to take the plastic ones, they are crap - use the aluminium. Given you are going to be working on the wall anyway, go and get some and do a test.

Battening is a second option but one I would avoid if posssible

mfceiling

+1 on the above.

Sticking boards is easier said than done

It's a job that you need to know what you are doing. Getting the boards level and plumb as well as making sure they are fixed properly and checking that the skirting board runs nice and flush at the floor is not a job for an amateur diy person in my opinion.

Spread

MartinCorcoran wrote: »

Unless you've done this before do not go down the blobbing route. It is a difficult job and results are often less than satisfactory.

I don't see why you cannot use mushroom fitting on cavity blocks. In fact I'd suggest they are potentially best suit to cavity blocks - I have used hundreds on cavities without any issues Just don't let anyone convince you to take the plastic ones, they are crap - use the aluminium. Given you are going to be working on the wall anyway, go and get some and do a test.

Battening is a second option but one I would avoid if posssible

The metal mushrooms can cause cold bridging. If it's hot indoors and very cold outside, beads of perspiration can form on the skimcoat at each mushroom. Believe me ........ I did this in a cavity block bathroom extension in my own house a few years ago. I eventually had to drive the mushrooms another 12mm into the insulation, put a dot of poly foam on top, cut it back when hard and reskim. The reason I used the metal ones in the fiirst place was because the rest of the house is 24" thick rendered stone.

BryanF

Spread wrote: »

The metal mushrooms can cause cold bridging. If it's hot indoors and very cold outside, beads of perspiration can form on the skimcoat at each mushroom. Believe me ........ I did this in a cavity block bathroom extension in my own house a few years ago. I eventually had to drive the mushrooms another 12mm into the insulation, put a dot of poly foam on top, cut it back when hard and reskim. The reason I used the metal ones in the fiirst place was because the rest of the house is 24" thick rendered stone.

its not the metal mushrooms one should be worried about, its the risk of interstitial condensation caused by the insulated dry-lining on a relatively cold wall surface. but at 25mm thickness Championc's probably ok, as the issue appears to more serious the lower the Uv attempted..

championc

mfceiling wrote: »

+1 on the above.

Sticking boards is easier said than done

It's a job that you need to know what you are doing. Getting the boards level and plumb as well as making sure they are fixed properly and checking that the skirting board runs nice and flush at the floor is not a job for an amateur diy person in my opinion.

Well thank god for this advise. I went the mushrooms route and luckily they were the metal type - drill the hole and bang them in. I went with the 50mm board so 90mm fixings. I was amazed that I only seemed he hit two or three cavities so I simply drilled another hole. I have one which I may not have drilled deep enough and seems pretty jammed in so will have to try and claw out. So I'm basically 90% finished with just a small area to finish.

Would anyone be able to advise as to how much should it roughly cost to have the whole wall now plastered. It's the Hall, Stairs and Landing (around Landing Window) of the gable end wall of a standard 3 bed semi ?


C

thunderdome

Is the breathable Knauf Insulation an option, would the wall perform as well as EPS approach. This appears breathable so no mould?

What other option are there on a 60mm partial fill cavity.