Air tightness

JB81

Hi there,

I am currently in the process of building an 1800 square foot bungalow and will be doing my upmost to make it energy efficient,
I have been pricing around for the air tightness side of things and my head is wrecked, i have got quotations for as high as €5500 ( although he dropped to €4500 without much fuss when i told him other prices i recieved ), and as low as €2000.
I just cannot understand how the range can be so much, for to me what seems like the same job, and i have checked the brand they use and they all check out ( Siga, Pro-clima etc... )

It is for the basic air tight membrane for the ceiling, block build so no wall membrane needed, and the taping of windows and doors ( approx 14 windows, 2 standard out side doors and one double glass door ).

Can anyone shed some light and let me know who they got to do it and approx how much

Thanks in advance
JB

JB81

Oh and no spot lights in the house at all....

thanks

Lemlin

I was pricing there a while ago and found the same. I think some installers are just out to rip people off.
One installer quoted me 4800 + VAT. The installer I went with in the end said he should be able to do the house for around 2k (depending on when he sees it ready for the membrane and the finish etc).
He also priced 350e for installing membrane to hollowcore slabs. Another installer mentioned 500 plus VAT!

Alot of places are reluctant to give a definite price until they see the house and its actually done. If you're in the Cavan/Meath area, I contacted a Siga rep and he told me a good installer. Pm me if you want details.

Also, its worth remembering you should add a scratch coat to walls before insulated slab is put on for airtightness. Every installer I contacted recommended that.

MicktheMan

Did any of the air tightness contractors guarantee a specific air tightness level when they were finished and include the air tightness test in the quote? Remember a decent garden shed would pass the current building regs for air permeability.

mr_edge_to_you

JB81 wrote: »

It is for the basic air tight membrane for the ceiling, block build so no wall membrane needed, and the taping of windows and doors ( approx 14 windows, 2 standard out side doors and one double glass door ).

Can anyone shed some light and let me know who they got to do it and approx how much

Thanks in advance
JB

our builder did the same job as you did for €1500. apparently the tape is very expensive. my father in law was using bits of it for odd jobs and i can see why. very very strong stuff.

delighted we did it. the house is like a sauna these days so i'm hoping in the water that it will help keep the heatpump operating hours to a minimum.

JB81

hi

I did ask about gaurantees and the like but the answers were very up in the air, i think it is fair to say that they cant do a proper test until all plastering is done and slabbing etc... but one did say they would do a smoke test so you would see any leaks through windows or into the attic so this is an idea. I will also be doing a thermal imaging at the end so this should help identify any probelms,

In relation to your reply Mr Edge, the main aim as you say of all this is to reduce the run time of the heat pump as much as possible,

In relation to your comment about scraqthc coat LEmlin, i wont be putting up insulated boards, my aim is that the internal block leaf will act as a thermal mass and hold any heat, I have a 200mm pump filled cavity and have closed the cavity at the top with a thermal block to help with any thermal bridging and heat loss to keep as much heat in the house for as long as possible

If it works.....

Thanks all

MicktheMan

JB81 wrote: »

hi

I did ask about gaurantees and the like but the answers were very up in the air, i think it is fair to say that they cant do a proper test until all plastering is done and slabbing etc... but one did say they would do a smoke test so you would see any leaks through windows or into the attic so this is an idea. I will also be doing a thermal imaging at the end so this should help identify any probelms,

No. An early airtightness test before slabbing etc is done will show where the airtight weaknesses are when it is relatively easy and inexpensive to fix. Waiting to test until the end will result in either a very expensive repair job or airtightnesss problems in a house you specifically paid out to have airtight!
Using trace smoke to find leaks should be a normal part of the test in any case.

beyondpassive

I find that the OSB3 15mm liner is a good solution, everybody 'gets it', on a comprehension level. Then again I would like it as I've never had to physically install it myself. 'Soldsold' has a great thread about fixing OSB3 12 or 15mmand there's a bit of work involved there. I do the odd airtightness test and so end up doing some remedial taping work during the testing. Moy do some good tapes along with the top of the range Siga and Intello tapes, for instance Moy and these are fairly straight forward to install. In some cases where we've been aiming to exceed the 0.6 ach@50pa airtighness, (about 10 times better than building regs, our clients have spent days taping every vapour barrier stable or OSB screw.

For a bungalow, you could put OSB under the ceiling joists and slab up to that, or if you have the head height you could create a services cavity for wiring and downlights. For airtighness the trap door (loft hatch) is critical and can be a huge source of heat loss. Celluse or 3 layers of 100mm mineral wool with builders paper between is a good solution, with a gangway to service tanks etc.

So if you have rooms in the roof, perhaps the roofer can do the airtightness barrier as OSB. This works quite well with cellulose, as mentioned before, the spec of 22mm softboard outside and 225-275 cellulose fill seems to be very effective. The initial capital costs are higher but this is easily justified in performance. The cellulose/softboard combination performs better than modelling would suggest. The detail of placing insulation boards between rafter and then composite board inside that, gives an apparent good spec, but in reality it performs way below expectations, also the insulation boards are nasty as materials for houses because of waste, offgassing, thermal storage etc.

RKQ

OP if we assume all Installers priced the same area to airtight, using the same tapes & membranes, to the same construction details then the only excuse for such a price difference is Labour.

We are in a recession but this does not mean construction is cheap. There are still many who want to earn a good days wage on those days they actually work.

There is little price difference between material / tape manufacturers.
Recommendation, experience and proven ability are worth considering when choosing an Installer.

soldsold

Pretty much all of the tapes work out around 1 euro per meter. So for an 8x4 sheet of OSB its 2440mm x 1220mm so 2.4+2.4+1.2+1.2 meters per sheet which is 7.2 meters of tape. Of course the tape covers joints between two boards so its 3.6 meters of tape per OSB board, or 3 euro 60 cent.

Add wastage (+0.001% in my case ), and the fact that the boards will need to be cut up to fill gaps (+20% say) and you are up to around 5 euro per OSB board. My dormer roof is about 400m2 and with the flat ceiling removing the need to OSB right up to the apex I used just under 2 pallets of OSB.

If I could just remember how many 15mm OSB sheets are supplied on a pallet I could multiply x 5 to give the approx euro cost of tapes?

Of course rolls of airtightness membrane have less joints than 8x4 boards so less tape needed in theory

Viking House

I think that's 140 sheets of OSB which is €700 worth of tape.

soldsold

That sounds about right...