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OT. Plasterboard Advice Needed
dan8400 - 21/3/11 at 02:27 PM

I have stripped my house back to bare brick due to the plaster/render being a hundred years old and falling off in my hands. I have been advised to use Insulated plaster boards (dot and dab method) by one chap and to use lats/plastic sheet/ rockwool type insulation and normal plaster board by another fella.

I am not looking to cut corners but I'm not looking to throw money away either. Which way (or another way) is best?

Or I welcome any other opinions/ suggestions

Thanks
Dan

JacksAvon - 21/3/11 at 02:37 PM

dpends on the level of dap, if any.
If you have damp have damp retarding plaster used.

If no damp replaster anyway.
I would never dot and dab, it's just nasty.

dan8400 - 21/3/11 at 02:42 PM

No damp. Surveyor said it was a really dry house. Had scratty previous owners unfortunately, coupled with really really old render/plaster


Dan

cliftyhanger - 21/3/11 at 02:44 PM

Is it a cavity wall construction? If not DO NOT dot'n'dab, you will just get damp problems.

I have used the batten wall/plastic membrane/plasterboad in old houses, it is quick, tidy and allows the brickwork to breathe, but probably not enough. Builders are all to quick to try to damp proof a wall. Old properties this rarely works. The ideal is a breathable plaster and breathable paints.

It all comes down to the house construction, but I reckon if not cavity wall you need a ventilated airgap. And a bit of insulation, then board.

dan8400 - 21/3/11 at 02:48 PM

Double brick no cavity. But no damp either. The house has a damp proof course.

martyn1137 - 21/3/11 at 03:45 PM

Better insulation value from preinsulated plasterboard in comparison to same thickness quilt. Also easier to take up minor variations in wall surface with dot and dab.

With both systems fixing the likes of cupboards, curtain rails etc will need special fittings.

rallyingden - 21/3/11 at 04:24 PM

There is nothing wrong with dot and dab, I have done the whole of my downstairs with it including my new kitchen extension. just made sure there was plenty of Dot where the kitchen cupboards were going to give something to fix into. Also as I am in a semi I used timer frame with insulation etc on the divinding walls for sound insulation.

Cheers
RD

[Edited on 21/3/11 by rallyingden]

HowardB - 21/3/11 at 04:35 PM

can I just put a word in for the PINKFIX foam system, use it in conjunction with either plaster board, or insulated board.

It is so simple, squirt onto the back of the board, let it set for a few mins and then press into place. It is also great for filling gaps and also forming across window frames, and other gaps.

If you want further info let me know, but the stuff is magic, easy to apply and clean. I can't re-iterate how good it is.

hope that helps

big-vee-twin - 21/3/11 at 05:29 PM

You need Gyproc thermaline 65mm or similar that will get you a reasonable U value.

It has 50mm insulation with 15mm plasterboard bonded to it

Guinness - 21/3/11 at 06:24 PM

quote:
Originally posted by big-vee-twin
You need Gyproc thermaline 65mm or similar that will get you a reasonable U value.

It has 50mm insulation with 15mm plasterboard bonded to it


What he said!

Basically you have a solid brick external wall. If you dot and dab a traditional plasterboard to the brickwork, you'll most likely end up with damp spots on the boards where the dabs are.

If you plaster straight onto the brickwork you won't be able to increase the insulation value of the wall.

A traditional approach has been to line the brickwork with a timber frame / battens / a vapour membrane and additional insulation quilt. The trouble with this approach is the time taken to build up the layers, and to get a decent level of insulation you need quite a bit of quilt, hence losing a fair bit of internal space from the room.

The high performance plasterboard with the insulation bonded to the back is the stuff you need. The high density foam takes care of both the insulation and the vapour barrier part of the wall. The insulation value is much higher per mm compared to quilt, so you lose less space from your room. Very quick install, just dot and dab and then a skim.

Have a look on the British Gypsum website for the thermaline board. You can get it in differing thicknesses of insulation to suit your needs / building regs. You should be able to find a set of instructions on there, with details showing what to do in corners etc.

Last time I bought thermaline, I had to buy a pallet full at a time, but if your room is a reasonable size that won't matter.

Just be careful with the detailing around ventilating the void you create between the brickwork and the plasterboard. You don't want interstatial condensation on your floorboards / ceiling. Also when cutting the boards you have to make sure the window reveals, internal and external corners work (and it's not as simple as it looks)!

HTH

dan8400 - 22/3/11 at 08:02 AM

Ok, so if I lat the walls with something like 50mm x 50mm (2" x 2" can I get some sort of solid board to fit in between the uprights? Something I can pre-cut on the sawing horse and slot in between before I board over? Would seem the easiest way in my mind. Just checked out the price of per-insulated plasterboards about £33 a sheet!!!!



Thanks
Dan

cliftyhanger - 22/3/11 at 08:13 AM

I have always used treated roofing battens, think they are 18mm thick. I would then pop a layer of vapour membrane over, and then a layer of celotex or whatever insulation. 25mm will give a good improvement, you may be able to get 10 or 15mm??Then plasterboard over the top.

I had a chappie who wanted to use 1" battens, and then cut 1" thick polystyrene to fit between. That is cheap, but I would want an airgap. I know you say there is no damp, but a solid wall needs to breathe. Nothing wrong with polystyrene insulation, just not as high value as cellotex, but I have used it for "economy" work (ie rented accomodation)

cliftyhanger - 22/3/11 at 08:19 AM

http://www.builditsecurepayment.co.uk/acatalog/Celotex_Tbreak_insulation_boards.html

looks cheap for boards, plus free delivery.

dan8400 - 22/3/11 at 08:27 AM

So, Clifty, do you put your insulation boards over the top of the latts or in between? Sorry for the dumb questions



Thanks
Dan

Mday41 - 22/3/11 at 09:35 AM

i live in a 9inch solid brickwork bungalow and im also a plasterer of ten years! the two best options for you would either be to re render and skim with putting the write additives in or to dot an dab but leave a vent so there can b some air flow behind the board in my opinion i would re render and skim as u can always fix to the wall easy and also feels solid. with dot an dab its easy to dent put holes in and scratch very easy! i feel over once on a job an put my head straight thro a wall i had just finished says it all!. where do you live as could have alook an advise!

dan8400 - 22/3/11 at 09:57 AM

I live north of Boston Lincs. Small farm in the middle of no-where lol

So you would dot and dab or render without additional insulation Mday41?

Also, welcome to the forum


Thanks
Dan

cliftyhanger - 22/3/11 at 11:33 AM

quote:
Originally posted by dan8400
So, Clifty, do you put your insulation boards over the top of the latts or in between? Sorry for the dumb questions



Thanks
Dan


Depends!
If tight on space I would use 18mm roofing battens with 12mm insulation between and then 12mm plasterboard over the top, costs you 30mm.
If not such an issue, same battens and 12 or thicker insulation over the top and finish with plasterboard.

I'll stick by my point that the walls DO need to breathe, it is how they were built. My dear Dad had to have some similar walls internally rendered (with admixture) and plastered over as specified by a numpty council chap who knew nothing of building construction. Caused condensation proplems from the beginning. My "simple" solution was to hack the plaster off, batten/vapour barrier/thin insulation/timber cladding. Worked well, and the cladding looks in place as it is a victorian house.

Worth doing a search on solid wall houses, you may get better advice froms the RICS website or similar. Or indeed specialists in period houses.

Liam546 - 20/1/14 at 10:18 PM

I have a solid wall victorian property which has had previous damp issues. I'm renovating the property and have stripped back all the plaster downstairs to a 1 meter height. The party wall of downstairs is a earthy, rubble clunch type construction.

I don't want to lose space by building a timber frame with ventilation gap, insulating and then plasterboarding. Do you think just a lime render on the 1m high brick work and then a lime skim all over will be ok? This will allow the wall to breathe hopefully but and I hopefully I won't get damp back. I know I won't gain any extra insulation with this method though.

slingshot2000 - 20/1/14 at 11:09 PM

Will this be a live axle rear end or an IRS chassis that you are building ?

Regards
Jon

loggyboy - 20/1/14 at 11:24 PM

Or a JCB?