The dreaded insulation topic...again

gummibear

Hi all,
I know this has been done to death but here I go anyway...
starting 4 bed dormer next week. 237sq.m. trying to nail down insulation spec to get as good a result as possible without completely breaking the bank:rolleyes: Plans allow for basic building reg specs. kingspan recommendations will cost a bomb so hoping for somewhere in between...

Ground floor External Walls: 60mm TW50 Cavity board (negligible performance diff between this and newer K8 which kingspan recommended)
plus 42.5mm K17 Dry-Lining Board

Ground floor Solid Floor with UFH: 100mm K3 Floorboard


First floor dwarf Walls and pitched Roof:
125mm TP10 between rafters (again negligible diff between this and recommended K7 boards)
plus 42.5mm K18 Dry-Lining Board under rafters and inside external dwarf walls...

the K range has crazy prices :eek: on it not taking into account the recent rise!!! I know there is no such thing as overkill on insulation but is this a happy medium to achieve a good level of insulation... i.e. roughly B1 rating standard on the insulation side of things?

sinnerboy

gummibear wrote: »

Hi all,
I know this has been done to death but here I go anyway...
starting 4 bed dormer next week. 237sq.m. trying to nail down insulation spec to get as good a result as possible without completely breaking the bank:rolleyes: Plans allow for basic building reg specs. kingspan recommendations will cost a bomb so hoping for somewhere in between...

Ground floor External Walls: 60mm TW50 Cavity board (negligible performance diff between this and newer K8 which kingspan recommended)
plus 42.5mm K17 Dry-Lining Board

Ground floor Solid Floor with UFH: 100mm K3 Floorboard


First floor dwarf Walls and pitched Roof:
125mm TP10 between rafters (again negligible diff between this and recommended K7 boards)
plus 42.5mm K18 Dry-Lining Board under rafters and inside external dwarf walls...

the K range has crazy prices :eek: on it not taking into account the recent rise!!! I know there is no such thing as overkill on insulation but is this a happy medium to achieve a good level of insulation... i.e. roughly B1 rating standard on the insulation side of things?

Ext wall
60 KS in cavity + 52.5 dry lining as follows 25x 50 battens + air tight membrane* then 40 ks - foil tape all joints - then plasterboard over

Ground floor
2 x 60 ks layers +75 screed over - use 60 ks vertical at screed edge
( use polythene layer below screed to protect ks )

Roof
125 ks between timbers then air tight membrane* then 80 ks - foil tape all joints - then plasterboard over . Use breather membrane over rafters , then counterbattens then battens and ventilate OVER the breather membrane
Remember - 25 continuous strip at roof overhangs and 5mm continuous at apex . Insulate wall plate to apex to wallplate and extend insulation into eaves overhang box . Fit flooring ( floorboards ) from wallplate to wallplate

Hit on €€€'s . shop around . There are 3 major producers of PIR insulation in ireland


* air tight membrane - use variable permeabilty type .

gummibear

Cheers sinnerboy, comprehensive as always!:) Much appreciated

guju121

Quick question about the edge insulation ...
I have just started laying floor insulation in a new build ( UFH to go on top ).
I am putting in edge insultion but am confused at exactly how to do it ...
At the moment I am cutting a strip wide enough to sit on the sub floor and be level with the finished screed, then I am butting the floor insulation up against it.
It is proving time consuming and difficult to cut the strips as the sub floor is a bit rough, so it is hard to get the top of the strips nice and level etc

Just wondering if this is the correct way of doing it, it seems that the guy leveling the concrete screed will have a difficult job if the top of the strips are not perfectly level and the right hight.

Would it be better to cut the strips wider so the top of the strip ends up higher than the finished screed level ?
Would it be better to lay the on the floor tight up against the walls and then add the edge insulation on top of it

All these jobs sound simple until you go to do them ...

Any advice would be appriciated

sydthebeat

guju121 wrote: »

1. Would it be better to lay the on the floor tight up against the walls and then add the edge insulation on top of it

2. All these jobs sound simple until you go to do them ...

1. yes. if you need to leave the vertical insulation down a bit its not the end of the world, the screeder will need to screed off the block.
2. i think you will find there no such thing as a simple job.

guju121

Thanks for advice, one other think, its a timber frame house so all the internal door openings have a timber sole plate going across them which is up to the level of the finished floor screed.
I was think of leaving them in to help with leveling the screed but it will leave a cold bridge down to the subfloor and also the plummer was complaining about them being in the way of the UFH pipes ( he would have to drill holes through them and feed the pipes through the holes ).
Do you think it would be best to cut them out and continue the insulation through the door openings or leave them in.
The timber frame company said I could do either and it wouldn't affect the stability of the walls.

Also when putting down 500 gauge polytine, what is the best way of holding it in place. I was thinking of running it up the wall higher than finished floor level and stapling it to the walls

Thanks again for the advice

sydthebeat

guju121 wrote: »

Also when putting down 500 gauge polytine, what is the best way of holding it in place. I was thinking of running it up the wall higher than finished floor level and stapling it to the walls

where are you putting this???

If this is supposed to be your DPM, damp proof membrane, under the insulation, then:
1. it needs to be at leat 1200 gauge
2. it needs to step up and over the inner block thats the finished floro level. A secondaory DPC should be placed on top and the sole plate for the TF should be fixed above.

guju121

It's not a DPM, this was put in before the subfloor. It's just to protect the insulation from the concrete screed.

sydthebeat

ok, this 'slipsheet' should be carried a min of 100mm up the wall...

obviously you wont have a wall at this stage so you may leave it loose.

also 500 gauge is the minimum spec for this as well, perhaps consider 1000 gauge?

guju121

Ok, what do you think about cutting out the sole plate a the door openings ? ...

sydthebeat

seeing as the TF crowd have said its ok then fire ahead....