air tight tape yes or no

cavanmann

hi i am building a air tight house and and i am wondering if i am wasteing money buying air tight tape which i will never get my return from or the benefit of i am going to seal around windows with a sealer and then plaster the porous block and them pin the 62 mm insulated slab on to block, the reason i asked these questions is that every one has different views and ideas when it comes to air tightness
need more info, is it worth it or am i simply spending money unnecessary

sydthebeat

you must have quite a thick window frame to be able to do that

cavanmann

sydthebeat wrote: »

you must have quite a thick window frame to be able to do that

Wondering what you mean syd

BryanF

cavanmann wrote: »

hi i am building a air tight house and and i am wondering if i am wasteing money buying air tight tape which i will never get my return from or the benefit of i am going to seal around windows with a sealer and then plaster the porous block and them pin the 62 mm insulated slab on to block, the reason i asked these questions is that every one has different views and ideas when it comes to air tightness
need more info, is it worth it or am i simply spending money unnecessary

your air-tightness layer is the plastered porous block right? so then how does the window frame 'seal' to the rough plastered block - i think you'll find in reality if your arch doesn't detail and specify this air-tightness issue, expanding foam will be 'ur only man' on site, and your air-tightness tester will be puffing smoke out through there when your all ready to paint..
why insulated slabs? I don't understand the logic to them in a new house? hows your thermal bridging looking?

Poor Uncle Tom

62mm insulated slab returned to meet the window frame at the reveals.

glenkeo

Hi
I would highly recommend the tape. Also get has much information has you can about air tightness I did my own house and it is pretty good but if I was to do it gain I would do a few things different. One place that is hard to get right is around the slab and cavity on first floor and any air that gets in between cleaning and slab will travel around and come out through fittings. Also the key holes in external doors you would not believe how much air came in through them, has you seal the house any small bit that is missed will really stand out. But it is well worth the effort

MicktheMan

cavanmann wrote: »

hi i am building a air tight house and and i am wondering if i am wasteing money buying air tight tape

What is your airtightness spec?

cavanmann

glenkeo wrote: »

Hi
I would highly recommend the tape. Also get has much information has you can about air tightness I did my own house and it is pretty good but if I was to do it gain I would do a few things different. One place that is hard to get right is around the slab and cavity on first floor and any air that gets in between cleaning and slab will travel around and come out through fittings. Also the key holes in external doors you would not believe how much air came in through them, has you seal the house any small bit that is missed will really stand out. But it is well worth the effort

Hi glenko

When I was putting in hollow core slabs I sealed all the ends of them that's was in cavity , I reason I done that Is because a guy that is doing air testing told me
What products did you use and how did you fix to block around windows
Thanks

sas

cavanmann wrote: »

Hi glenko

When I was putting in hollow core slabs I sealed all the ends of them that's was in cavity , I reason I done that Is because a guy that is doing air testing told me
What products did you use and how did you fix to block around windows
Thanks

Either you misunderstood him or you were given poor advice.

There is a specific detail for sealing around hollowcore and what you've done isn't it.

Sealing the ends of the slabs only prevents air moving through the slabs. What about above them, below them or between them? Plastering up to or down to the slabs doesn't create a good seal.

There isn't much you can do now however that's going to make much difference.

Granted, as you came on here before you fitted the hollowcore, got the correct advice and ignored it, I'm not sure what you stand to gain this time.
http://www.boards.ie/vbulletin/showthread.php?p=71880574

With regards to your windows, use the airtightness tape but talk to the technical dept. of the specific product suppliers so that you get the correct advice on how to fit it.

You say you're building an airtight house. What result on your blower door test are you aiming for?

glenkeo

Hi I know when we do self builds we try to do has much as we can our self’s to save money but in air tightness and insulation is the one place I would get has much detail well ahead of time and don’t leave anything to chance, I am very happy with my house in second winter now and it holds the heat very well but I did a lot on both. On the windows I used a tape that has a 12mm side and a 35mm side the folds at right angle also used a tube of blue stuff(can't think of right name) that went on block first, the 12mm goes on frame and was covered by plaster and finish coat. I was in too many rented house with the curtains blowing out from wall when the plaster shrinks back from the frame and let’s air in and under the window board. There will be people on here that will have a lot more detail than myself.

tred

cavanmann wrote: »

hi i am building a air tight house and and i am wondering if i am wasteing money buying air tight tape which i will never get my return from or the benefit of i am going to seal around windows with a sealer and then plaster the porous block and them pin the 62 mm insulated slab on to block, the reason i asked these questions is that every one has different views and ideas when it comes to air tightness
need more info, is it worth it or am i simply spending money unnecessary

Best thing i ever did. You can insulate the hell out of your hosue, but if if you have cold draughts around windows, roof space then your wasting your time....

sydthebeat

cavanmann wrote: »

Wondering what you mean syd

youve said....

i am going to seal around windows with a sealer and then plaster the porous block and them pin the 62 mm insulated slab on to block,

That means the internal face of your jamb will be covering your window frame by approx 70mm ...... this is hardly correct.

Taping the windows is the easiest bit of an air tightness stragety. using membranes over ceilings etc is a lot more expensive and time consuming.

what "sealer" did you use for the windows?

sas

sydthebeat wrote: »

That means the internal face of your jamb will be covering your window frame by approx 70mm ...... this is hardly correct.

My foreman recently visited a site where the block layer had kept the internal opening wider (and possibly higher) than the external opening. This was done specifically to accomadate thick internal insulation. Maybe something like that was done.

sydthebeat

sas wrote: »

My foreman recently visited a site where the block layer had kept the internal opening wider (and possibly higher) than the external opening. This was done specifically to accomadate thick internal insulation. Maybe something like that was done.

maybe

castleking1

I have a wider internal opening than the external by 25mm on each side and used 70mm frames to accommodate 37.5mm insulated board (overall thick) on reveals. I have 62.5mm on the inside of the rest of the external walls. I then have put airtight tape around windows. I didn't put insulated board on the heads of windows as the lintels would be stepped. Just 12mm plasterboard here.

Poor Uncle Tom

castleking1 wrote: »

I have a wider internal opening than the external by 25mm on each side and used 70mm frames to accommodate 37.5mm insulated board (overall thick) on reveals. I have 62.5mm on the inside of the rest of the external walls. I then have put airtight tape around windows. I didn't put insulated board on the heads of windows as the lintels would be stepped. Just 12mm plasterboard here.

So is the window frame:

1. flush with the inside leaf, which would mean 25mm of the frame is effectively behind the outer leaf.

or

2. flush with the outer leaf, which means the fixing straps for the windows will interfere with the returned insulated slabs on the reveals and the windows will need 'filling in' between the frame and internal leaf of blockwork.

BryanF

this is worth a look

http://www.greenbuildingadvisor.com/system/files/sites/default/files/Kruger_9781111135959_ch04.pdf

American, but alot of the principles are transferable

castleking1

Hi uncle tom
No the window frame is 10mm shy of inner leaf on both sides so it is 15mm or so wider than the external leaf. Thus the insulated board doesn't cover out to slips on window on inside and so the external render doesn't cover too much of the external frame.

yellow50HX

this may have been answered before but i'm in a similar boat.

was goign to get the tape to do around the windows and doors but have filled the gaps with expanding foam (wider gaps) and sealant (smaller gaps). will be putting 62mm plaster board on inside of walls with the thinner board back into the windows and doors. The plan is to pumps the cavity with beads with adhesive. am i correct in assuming if the cavity is filled right that his will seal any gaps in the wall around the jionts and windows meaning i wont need to run loads of tape around the jionts?

was planning on putting a vapour barrier under the ceiling slab and sealing the jionts on that would be coming through that.

Rushy Fields

Is siga a far superior product to the likes of dafa, airstop, pro clima, etc it seems to be more costly than these other products. should i steer clear from the less expensive ones. P M me if anyone has any comments.

BryanF

nealger wrote: »

Is siga a far superior product to the likes of dafa, airstop, pro clima, etc it seems to be more costly than these other products. should i steer clear from the less expensive ones. P M me if anyone has any comments.

Look at the warranty / lifespan.

fclauson

yellow50HX wrote: »

this may have been answered before but i'm in a similar boat.

was goign to get the tape to do around the windows and doors but have filled the gaps with expanding foam (wider gaps) and sealant (smaller gaps). will be putting 62mm plaster board on inside of walls with the thinner board back into the windows and doors. The plan is to pumps the cavity with beads with adhesive. am i correct in assuming if the cavity is filled right that his will seal any gaps in the wall around the jionts and windows meaning i wont need to run loads of tape around the jionts?

was planning on putting a vapour barrier under the ceiling slab and sealing the jionts on that would be coming through that.

Expanding foam IS NOT air tight

have just had my house tested (0.54 ACH) and guess where there was one of the leaks - aroudn a bit of expanding foam used on a floor light fitting

do not cod you self - if you are going for a decent ACH then use the products which can achieve this

yellow50HX

fclauson wrote: »

Expanding foam IS NOT air tight

have just had my house tested (0.54 ACH) and guess where there was one of the leaks - aroudn a bit of expanding foam used on a floor light fitting

do not cod you self - if you are going for a decent ACH then use the products which can achieve this

cheers for that. was looking on-line at the siga tape but was going to hold tough till i knew if i needed it or not. will look to seal around the windows with sealant again anyway once the plaster board goes on, and then tape up the junctions and holes on the drylining before skimming

Glengormanjay

High guys
Surely there is foam out there that is air tight or at least close to it?
My problem is my builder put the front gable end floor joist (engineered steel braced) right up against the front block wall, no room to plaster finish. I know I can get a membrane between the joist and wall for 90% of its length but the two corners will be very difficult to seal. I am hoping that I can buy a couple of cans of spray on closed cell foam that will seal up all detail in those two corners. When I say spray on I mean like paint spray as opposed to the usual nozzle tube type application.
Anybody got any advice on where to get such spray on foam without going to the whole hog and hiring a contractor.

Always grateful for board advice.
J

fclauson

If its a paintable space and only small then you could try some form of bitch roof paint - just a thought

Glengormanjay

I think I need a spray of airtight expanding material to cover all opes, cracks joints etc