# Removing old drylining before new goes up



## CBGB (10 Jul 2010)

Hi 

I want to internally insulate my house. Currently on most walls is cavity block but sounds like some level of drylining internally. Its a 60's house so am assuming theres no insulation with the drylining. 
If I want to now internally insulate should I remove the original drylining first? If we didnt would it lead to problems with condensation build up between the two layers of drylining?

Cheers


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## Peter Sweeny (10 Jul 2010)

One of the advantages of removing the original dry-lining is to save on internal space.
If there is a vapour barrier immediately inside the new dry-lining this should resolve condensation issues under most circumstances.

You say that you have cavity block walls, you should check out the differences between the final u-value ratings on the exterior walls if you,

i) Just get the cavity between the block walls insulated, or
ii) Insulated the interior walls

The cost of insulating interior walls correctly including solving cold bridging issues around doors and window openings, redecorations, wiring, likely removal and refitting of kitchen and bathroom presses, bathtubs, showers, sinks, etc will be significantly more expensive then insulating a cavity wall. You will want to make sure that the costs involved justify the extra expenditure that it will entail


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## hopalong (11 Jul 2010)

how does the vapour barrier work,is it ordinary plastic sheeting,and does the moisture lodge between the plastic and the blockwork.


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## Peter Sweeny (11 Jul 2010)

With modern insulated dry-lined plasterboards the vapour barrier is normally placed during the manufacturing process between the dry-lining and the warm side of the rigid insulation.
If installed correctly this should prevent moisture from within the house penetrating the newly fitted insulated dry-lining.
Check with suppliers technical brochure and installation procedures before fitting.


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## CBGB (11 Jul 2010)

Thanks for comments. I meant that the wall is the large blocks with cavity in them as opposed to cavity wall so there is no space to place insulation between them. 

I reckon it will add a lot to the costs to get it removed but from what I can gather it seems to be the proper way to do it. we're refitting kitchens and bathrooms, wardrobes etc so its a good time to do it too.


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## rockofages (13 Jul 2010)

If the walls have original drylinging the chances are it's ordinary plaster board slabs held on with blobs of plaster. It has no insulating properties whatsoever and is only for aesthetics.

If you want to put up insulated plasterboard, then that old stuff has to come off.

To be sure that it's blobbed, just knock around on a wall gently (ie with your knuckle) - it will sound hollow where there are no blobs, and solid where there are blobs.


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## CBGB (13 Jul 2010)

cheers. I'll go blob hunting tonight!.
Would anyone have any idea how much that sort of job would cost for a standard size (95sq.m) 3 bed semi? It sounds like a big job but when you take away window area there not much wall area on the front and back. The detached-side wall obviously is a lot of work.


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## rockofages (13 Jul 2010)

Which job?

You can remove the old stuff yourself.

The €2500 SEI grant for internal drylining would go a long way towards paying for the new stuff.


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## CBGB (13 Jul 2010)

I would have thought taking off plasterboard on external wall would be a bit above my grade of DIY knowledge. 

Was wondering a price for removing old and putting new insulated slabs to meet regs. 

Would it save much to remove the old stuff myself versus potential mess ups?


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## rockofages (16 Jul 2010)

CBGB said:


> Would it save much to remove the old stuff myself versus potential mess ups?


There's not much you can do wrong, tho it is moderately hard work.

Your best course of action is to talk to the SEI-approved contractor that will be doing the drylining.


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## wastetech (25 Oct 2010)

Get rid of the old dry lining!!
Even though ours had a vapour barrier between the plasterboard and the insulation, we got DRY ROT in the dry lining support timbers within 11 months.  Funny thing, it was worse where the vapour barrier was than on the section of wall without it. You could draw a straight line where the mass of hyphae finished. Our Building Consultant said that the vapour barrier stopped the wall from breathing and as soon as the moisture reaches 22%, the Dry Rot has a party and invites all its friends!!
It cost us £3000 to rip out wall, floor and ceilings and replace them.


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