I have a solid wall extension which didnt have any form of damp proofing when built in 1943. recently i've had dpc under new concrete floor and dpc injected into the bricks. the source of the damp we believe was partially the room had never dried out from a significant burst over many days last year of a main water pipe a leaking roof and that the house was empty and closed for about 8 months. This resulted in crumbling and patchy plaster.

one of the walls had a higher than normal damp reading and this has been lined with a product to about 1 meter which i can only describe as looking like bubble wrap (sorry dont know the name)

We were removing the plaster to 1 meter but as the water pipe ran from ceiling level the damage to the plaster was higher, and over the other side of the room we had to also remove more as the damage was at ceiling height - so currently all three walls are back to brick.

First question, before i start to think of plaster / plasterboard, do i need any product to prevent future damp where the floor meets the walls?

Next, i'm looking at insulated plasterboard, the walls are 280mm think and the main house 300mm, what thickness plasterboard should i ideally be looking at to provide a good warm room - it will be a kitchen, the energy saving trust appear to recommend 70mm

Lastly, should i cover the walls with any form of moisture preventative or sealing product or plaster them prior to plasterboard? I'm doing this project in conjunction with a friend who is a lot more experienced than me, he is recommending now we have the dodgy plaster off and back to brick that we 'dab and dot' direct to the brick. reading the gyproc installation guide they do give this as an option using driliner tl.
However following their installation matrix they kind of recommend gypliner which appears to be a metal framework to attach the plasterboard to.

Lastly, ventilation. the room will be the kitchen, previously it has been unheated though the property now has central heating, currently there are two air bricks at just short of ceiling height, should these be kept, added to or removed?

any advice, thoughts or guidance appreciated

Dot and dab would be your best option, make sure to leave a gap where the board meets the floor so you dont get any rising damp.

The DPC injection you had into the walls should be sufficent, espically if you are dot and dabbing.

You can keep the air bricks, no need to cut out the plasterboard to match though (you could if you wanted to and cover with a plastic vent panel. The more airflow the better. But like I said, if all the walls have been treated you havent got to much to worry about.

If the walls havent been treated all over you could render and set with waterproofer, or battern the wall first and fix the plasterboard to the battern. If the walls are still damp, then where you appply the dots will show through onto the boards.

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Gypliner allthe way, although Richter system is cheaper and there isn't much difference. Try minsters insulation or sheffins.

You need aviation snips ( £ 4 from toolstation) and it is easier than carpentry, lighter and it doesn't absorb water, so you can put it on, screw on the insulated plasterboard, lifting half an inch to prevent the board absorbing any residual moisture. When you install your framework, make sure you fix to the wall above the bubblewrap stuff so that you don't compromise it.

Building control should have a spec which you should follow for the insulation. When you have boarded, cut new vent covers in to the plasterboard where the two airbricks are.

I'll post a picture when i get home as this may help..

if i go with render to seal the walls first, any recomendations on off the shelf products i can look at?

Also, if i go with the render, will this surface be suitable for dab and dot? reason i ask is (and i may have read wrong) the gypliner appears to be roughtly 70mm, then 70mm insulation backed with 12.5mm plasterboard, this is going to make for a thick wall?

Also, you mention BC, i checked before i started this, and although we've got a building notice in for the roof due to install of roof lights, i asked about the walls prior to this, at the time stating the plaster needed to come off as it was damaged and for damp proofing. They said i didnt need to submit a notice for this as they'd class it as repairs. My intention is to insulate to make a nice warm room, try to kill the damp and save some money on heating - am i taking a too simplistic view? i'm finding building control a nightmare tbh, doesnt matter if i'm trying to DIY, hire professionals, i get a different answer constantly on what is expected of me from BC and none BC people.

Thanks for all the advice so far :)
Chris

The building control spec is a useful guide. I wasn't suggesting you actually instruct them because that would be silly.

The gypliner is a maximum of 70mm. When fitted, it can be as little as 25mm. This link shows the bracket and you can see that it is adjustable (by bending). This allows you to follow the contours of the wall to create a perfectly flat inner partition.

http://buildingmaterials.co.uk/Metal-St ... ieces.html

Metal grid systems are not popular in the UK, although I don't use timber any more because it is more expensive, more difficult, heavier, harder to transport, isn't damp proof, takes longer and isn't as straight.

Thanks, hadn't realised that was how it fitted.