Insulating Internal Dorma Wall

[chojin360]

Hiya

i have done some searching and reading and really just want to confirm a few things

we are redecorating a bedroom in our house and we are going to get it re-skimmed - so whilst im making a mess i thought i would insulate one of the walls ( and the fact that the room is bloody freezing !! )

so ....

Its a 1970 house with a dorma built in prob 1975 and i dont think they heard of insulation in those days

we have recently had the dorma reclad in plastic and insualted but its still not retaining any heat

so is it worth while studding out one of the walls and insulating it ?? im thinking that something is better than nothing - but on the flip side of the coin - if im only doing one wall - will the heat just escape from somewhere else ( like thru the roof )

the wall in question is the wall between me and the neighbour - so in theory its half wall and half dorma ( if that makes sense )

if you place your hand on the wall in different parts you can feel the difference in temperate as to what is brick and what is the dorma

you can also feel a difference in temperature with the ceiling of the dorma ( outside ) and the part of the ceiling which is effectively the loft ( which has 200mm of insulation in it )

the plan is ( so correct me if im wrong ! )

1 - leave the plaster on the wall ( surely it acts as extra insulation )
2 - screw 2*2 battons to the wall in a frame
3 - fill the space with 50mm polystrene sheets
4 - work out where i want extra plug sockets and put some 35-40mm tubing in place so its easy to run the new cables
5 - screw plasterboard to the front
6 - phone plaster and get it all reskimmed

im also tempted to add a 2*2 frame and do the same thing to the ceiling of the dorma ( the ceiling is split by a perlin so its easy to work out what is dorma ceiling and what is directly under the loft )

does this sound about right - or i have i missed anything ( damp barriers etc..)

if all this is a workable solution and fixes the problem then i might be tempted to do the other wall so that the dorma side both have internal insulation ( i will only loose 6-7 inch off the width of the room and that not a problem aslong as its warm ! )

sorry about the long post - but i would rather do it right the first time !!

thanks

Stu

 

[^woody^]

Generally avoid polystyrene - its a bit inefficient. Cheap, but not much use unless really thick

Use something like celotex or kingspan.

I would aim for as much as possible - minimum 100mm in total - 50mm between studs and 50mm across the face, then plasterboard.

Remember to maintain any fire precautions if necessary (as this is a party wall), and maintain a vapour barrier if there is a timber frame - ie tape joints if using celotex/kingspan

 

[chojin360]

ref the polystyrene - that was probably bad wording from me !! - i would be looking at using something like :

http://www.wickes.co.uk/General-Con...n/General-Purpose-Insulation-Slab/invt/161197

which im assuming is a tad better

is there a reason for putting 50mm accross the face - is this to remove the cold spots that the batons cause ???

is the thickness of the insulation relevant to the heat retained ?? does common sense come into play that 100mm is better than 50mm but then 150mm is better than 100mm

is 100mm twice as effective as 50mm ??

surely 50mm is better than nothing - or would i see a marginal impact and the money better spent in just keeping the heating on for longer ??

the wall that im looking at doing is certainly no more than 9 ft tall and is about 9 foot wide - so i would be looking at using about 15 slabs ( based on that being 3 high and 5 wide ) - so costing will be about £60 , then timber and some plasterboard sheets

is it possible to save £100 over xx years with doing this to just the one wall - or im a best ( as i said ) using the £100 to use the heating more often ??

Stu

 

[^woody^]

Yes its just a commercial decision and you just have to do the maths with regards to cost of doing the work or just cranking up the heat. Celotex will be about £3 per m2 extra than that wickes rockwool

2x or 3x insulation thickness does not translate to 2x or 3x heat saving, but its a guide.

But in context, if you are only insulating one or a small part of a room, then heat will be lost elsewhere, so you have to decide the benefits of insulating in isolation.

 

[chojin360]

But in context, if you are only insulating one or a small part of a room, then heat will be lost elsewhere, so you have to decide the benefits of insulating in isolation.

thats the thing thats preying on my mind - is it actually worth just doing the one wall - the only thing that says its a good idea is that ..

1 - wall with window ( this is insulated when cladded and i have insulated under the window behind the plasterboard via a crawl space )
2 - the rear wall - this is a 100% internal wall
3 - the opposite wall that im thinking of doing with a door in it - again this is an internal wall ALTHOUGH some of it is still the dorma )

in an ideal world the best bet would be to do the 2 walls that have the dorma side ( not sure how to deal with the side with the door ) and the dorma ceiling

i need to weigh up the pro's and con's at this point - but i just needed to make sure that the direction i was heading was correct and that i hadnt missed anything !

Stu