100mm insulation board in 95mm stud wall...

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hi, did do a search but nothing really what i needed.

doing some home renovation and our insulation board is around 5mm bigger than the cavity.

it's obviously expensive stuff for us at least, we've p'boarded one side so the excess is sticking out the other side. so when it comes to boarding this side, in a sense it is going to be floating, we will have to put the screws in less tight so the board doesn't bow/bend/break.

if enough screws are used, will the ''floating'' plasterboard be an issue? i.e. it'll be 5mm from the studs and flush to the insulation board.

if this is a big issue you suggest fixing, we could cut the insulation in the middle (to keep the foiled sides) and shave the excess off. but to saw through all that, is quite tiring and time consuming and obviously means we're cutting up some expensive insulation..

so my question is quite obvious, ''float'' the P'board and use more screws, or cut the insulation to fit, presuming we are not going to buy anything smaller etc.

many thanks. the room is dividing a hallway and bedroom. and will also be used between a bedroom and bathroom.

and obvioulsy i mean cut lengths ways, to remove some width, basically slicing it down the middle so we have 2x50mm and then shaving 3mm off each of the unfoiled sides and then sandwiching them together... yes the 'planner' in the family was a bit foolish..

OR.. would you suggest... getting some 10mm strips of wood and going over the stud wall, then the pboard then actually is flush to something round the edges and not pushed out by the insulation
cheers
 
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Agree with above answer but you're throwing money away insulating between heated rooms, you don't need thermal insulation between internal rooms unless it's a garage or something on one side.
You might want acoustic insulation though
Do your wallet a favour and return the rest of the celotex and use mineral wool in the void instead.
 
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OR.. would you suggest... getting some 10mm strips of wood and going over the stud wall, then the pboard then actually is flush to something round the edges and not pushed out by the insulation
cheers
I'm not sure it will be an issue unless you struggle to 'seat' the screws properly (without popping) I guess. Don't throw your money away on wood strips. Just buy a 9.5mm plasterboard and cut that into strips.
 

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You want acoustic insulation on internal walls. 100mm could be squashed down to fit.

Reuse boards elsewhere or sell.
 
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It's not worth the OP or a thread. Put the stuff in, screw the boards on.
 
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It's not worth the OP or a thread. Put the stuff in, screw the boards on.
well if i couldnt find a decent answer, and if asking/getting help benefits me, then it's worth the 0.00002 bytes of data on this site, so thanks for the comment.

as for the others, cheers for replying, my dad just went ahead and bought it already.. 100mm with 95mm wood, well done i said , so we will end up using it im sure, i dont like the idea of trying to bend around the insulation but not fully tightening the screws and will probably go with the strips which should be pretty inexpensive.... in comparison not sure about reselling as he's purchased now and nearly 60, set in his ways. it'll all get rammed in somewhere, all good, once plastered no one will ever know hopefully.. as for not needing to really insulate, i know a bit OTT, but is what it is, cheers.

we have the outside wall then 50mm of 'kingspan/celotex' then nothing but plasterboard, envisage any problems there??? damp wise etc.. cheers
 
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I like the plasterboard strips idea, uses up the offcuts (which would otherwise end up as contaminated waste), but some people seem to like chucking money.

In the old days, before fancy planed timber, a sawn 4x2 was 4" (just over 100mm) but the insulation makers don't seem to have realised no-one uses it any more.
 
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I'm not sure how 9.5mm of plasterboard will compress into 5mm of space o_O, but I do wonder which would be more likely to cause pattern staining - x mm of plasterboard or timber, or the same space full of air?
 
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didn't think of using plasterboard strips.. wood seems a bit more secure, but a good suggestion and something to consider, could potentially do wood strips vertically and save some cash on horizontal pboard strips.. presuming they're the same thickness.. probably not worth the messing about giving the cost of the wood, but still an idea... dont worry it's our own house lol.

and as for staining, not something i know about, but thanks for bringing it up, if we extend the internal frame with some strips, i suppose there will be a very small area of dead air.. where the lets say inch strip is fitted onto the 4 inch 'stud' so there will be say 3 inches of dead space running veritcally.. , it's an internal wall and the whole ceiling above has 100mm board too, so think we'll just hope for the best, could be wrong but doubt there'll be much problem here.. maybe you mean for the outside wall??

the outside wall as mentioned, we have external wall, 50mm celotex, foam any gaps then normal plasterboard, if u envisage staining on this wall or any problems let me know cheers..
 
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When constructing a wall, you need to be mindful of internal and external condensation risk. Air voids internally create a risk of internal condensation forming on cold surfaces, whilst different materials on the internal face create a risk of actual surface condensation or a lesser phenomenon of dark stains forming.
 
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In the old days, before fancy planed timber, a sawn 4x2 was 4" (just over 100mm) but the insulation makers don't seem to have realised no-one uses it any more.
Nor have door casing manu's caught on. Extra bag of Multi-finish for every stud wall doorway.:)
 
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I do wonder which would be more likely to cause pattern staining - x mm of plasterboard or timber, or the same space full of air?
Surely you mean x + stud thickness? Are you saying that ordinarily plasterboard should not be in contact with the studs? The options for further (anti-shadow staining) insulation across the studs has not been discussed.o_O

Bizarre post Woods.
 
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Surely you mean x + stud thickness? Are you saying that ordinarily plasterboard should not be in contact with the studs? The options for further (anti-shadow staining) insulation across the studs has not been discussed.o_O

Bizarre post Woods.
The studs are a thermal bridge. Plain and simple.

As is any plasterboard strip on the studs to close the gap
 
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The studs are a thermal bridge. Plain and simple.

As is any plasterboard strip on the studs to close the gap
Yes quite. There would be a thermal bridge with or without the strips and the strips are still just as useful. And cheaper than wood ones.
 
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