Insulation -- Dry lining

selfdiy

Hi,
I've been reading through some of the older threads, which are very good and detailed. But I still have a few questions.

I've got a standard 100/100/100 cavity block construction house, (the block work is almost complete)

I originally planned to Dry Line the house. During the construction I decided that I'd put 60 mm king span tw 50 in the cavity (while we were at it).

1. What is the best method of drylining with my current situation?
2. Is there a chance that damp/mould can occur between the two layers of insulation?
3. Should I be using a vapour barrier?
4. Should I be leaving a ventilation gap at the back?
5. Should I leave a service gap at the front.

I'd like to do the drylining myself if possible (I'm not a builder but I can mange to get most things done reasonably well), have people done it before, found it easy or hard?

Sorry for the bunch of questions and long post!!
Any advice would be great though....

RKQ

selfdiy wrote: »

1. What is the best method of drylining with my current situation?

Add 30mm foil xtratherm + slab to interior wall or as per your BER advisors recommendations.

selfdiy wrote: »

2. Is there a chance that damp/mould can occur between the two layers of insulation?

IMO no! Though this is an area of interesting debate.

selfdiy wrote: »

3. Should I be using a vapour barrier?

If possible yes! I have a similar construction in my garage, so as usual I'll put my money where my mouth is and experiment with 30mm foil mushroom fixed to block, aluminium tape all joints in foil boards as vp and slab with mushroom fixings ( timber battens on blockwork for proposed shelves, skirting, etc you would have to consider curtain poles, wall units etc etc)

selfdiy wrote: »

4. Should I be leaving a ventilation gap at the back?

I don't think so - I'm open to debate but the gap makes construction "overly" complicated. (Battening out, sealing around services etc) IMO the inner leaf will be warm anyway as 30mm isn't a huge amount of insulation.

selfdiy wrote: »

5. Should I leave a service gap at the front.

Depents on insulation manufactureres recommendation. I believe Kingspan recommend electric service conduits on block work wall.

I'm sure others will disagree (which is good for debate) even though your questions have remained unanswered for over 27 hours!

You have raised some very good questions, especially 2. & 4. which are difficult to even get definative answers from the main insulation Manufacturers. The simplist construction to comply will win out in the end - wider cavity or dry-line?

Poor Uncle Tom

selfdiy wrote: »

1. What is the best method of drylining with my current situation?

I believe it would be insulated plasterboard on a vapour check on the wall, discuss thickness with BER assesor.

selfdiy wrote: »

2. Is there a chance that damp/mould can occur between the two layers of insulation?

Anywhere condensation or moisture can get, mould can follow. If the plasterboard gets sealed properly and the foil or moisture barrier is installed properly then interstital condensation should not occur and mould should not be a problem, good ventilation for the room is also essential.

selfdiy wrote: »

3. Should I be using a vapour barrier?

Yes.

selfdiy wrote: »

4. Should I be leaving a ventilation gap at the back?

No. A ventilation gap at the back of drylining is usually to allow supporting battens to breath through air circulation. Any battens used should be treated for what they are in this case, grounds only.

selfdiy wrote: »

5. Should I leave a service gap at the front.

No. Electrics, etc., are usually fixed to the blockwork and the insulated plasterboard cut around them.

selfdiy wrote: »

I'd like to do the drylining myself if possible (I'm not a builder but I can mange to get most things done reasonably well)

I'm sorry, but reasonably well is not good enough. This is a one time deal and if it's not done properly you might as well not do it at all, best leave it too the people who are well used to it, and if something goes wrong you have someone to come back on.

selfdiy

Hi Many Thanks for the responses,

Here's what I have taken from them,

Chase walls for electricks.
Put on vapour barrier.
Add battons where cabinets may need to be supported.
Then Insulation with plaster board.

One last question, a raft foundation was used and the finished floors are not in yet (under floor heating will also be used) does the drylining go all the way down to the sub floor (raft) or does it go in after the finished floors are layed?

Cheers...

RKQ

All floor slabs are required to have perimeter floor insulation, installed vertically around the perimeter of the dwelling. This is especially important with underfloor heating.
Dryling will join with the floor insulation.

Seek advice from BER Assessor and your Certifier.

sunnysoutheast

I seem to remember from the spec. sheets for the Xtratherm boards we used that they were adamant that the boards must not be chased or cut for services.

Either battens should be used to provide a cavity or the walls should be chased.

I also thought that the foil facings acted as a vapour barrier so a separate one isn't needed (but would do no harm I assume).

SSE

sydthebeat

sunnysoutheast wrote: »

I seem to remember from the spec. sheets for the Xtratherm boards we used that they were adamant that the boards must not be chased or cut for services.

Either battens should be used to provide a cavity or the walls should be chased.

I also thought that the foil facings acted as a vapour barrier so a separate one isn't needed (but would do no harm I assume).

SSE

a vapour barrier should always be continuous and uninterrupted... so foil back plasterboard doesnt act as an adequate vapour barrier IMHO.

Poor Uncle Tom

selfdiy wrote: »

Chase walls for electricks..

I think the op understands the cutting of slabs and insulation referred to was to bring socket and switch boxes to the outside of the drylined finished wall surface for use.

selfdiy

Hi,
I understand that the walls should be chased for the wires and that the sockets need to come out to meet the outer face.

I've also been in contact with a BER accessor, I'll be getting two blower tests done, I havn't figured out what product to use for the drylining yet though.

I'd love to see somewhere where drylining has been done to a high standard, particularly around the windows and doors.

I'm worried no matter how careful the installer is when I'm there, they may not be that careful when I'm not. Most tradesmen like to get in and out quick (which I can't blame them for .. time is money)... I think to do the vapour barrier right could take some time to do with all the detail.

The blower test in anycase should help locate problems...

Just out of curiosity are these blower units expensive? they dont seem to have alot to them....

No6

About 5k plus training last time I looked, You are not required to have pressure test done unless your house was lodged for planning after 1st July 2008. How much is the pressure testing costing you and was it reccomended to you or were you told it is required?? as looking at your posts you are keen to save money not spend it!!

Don't do the drylining yourself unless you have done it before, you'll end up paying the plasterer a fortune to try and get the walls level!!

selfdiy

Hi NO6,
It will work out a little less that a 1000 euro for two blower test, a BER Cert and some advice on what the different products will achieve.

Does that sound like alot?
How much should it cost.

I dont mind spending as long as I'm getting value

getmoving

Jey Seldiy,

Did you DIY it? any pics?

GM

selfdiy

Hi getmoving,
Decided to leave it to the plasterer to dryline as well. It hasn't been done yet so no pics.

Good luck with your project...