Stopping a draught under a window sill

Iwannahurl

Ireland's rubbish construction standards/practices never cease to amaze and annoy me.

I live in a timber frame house, and I have noticed that there can be a significant draught coming from underneath some windows, the severity depending on weather conditions.

The draught is coming up between the PVC window and the internal hardwood sill/ledge. Clearly there is no seal underneath, which is just stupid, lazy and wasteful of energy IMO.

I'd prefer to seal the primary source of the draught, rather than the gap around the wooden sill itself.

How easy is it to lift a timber window sill/ledge? What might I expect to see underneath in a timber frame house built in 2002? What kind of sealing compound should I use, and where should I apply it?

Thanks in advance for any advice or tips.

vicwatson

Yes, I know exactly what you are talking about. It's happening because the wooden window sill is placed atop the cavity and of course in that cavity there is tonnes and tonnes of air moving around (fed by the vents to the outside your house).

So, the air comes in the vents into the cavity and "leaks" into the house via the following route - think downlighters, think window sills at windows and underneath, think if plaster hasn't been completed all the way to the ground behind skirting boards, think light switches, think plug sockets, think extractor fans in kitchen and bathroom, one then also has air vents direct from outside to each room, and they want use to go green and save on our heating bills, how the hell can we do that when there is so much unnecessary air/draughts coming into timber frame houses IMO? :mad::mad:

What I did was use silicone along underneath the sill and where the sill touches the pvc window. The finish is fine, it looks good infact.

If you remove the sill you will see the cavity - i.e. the gap between the timber frame on the inside and the block outerleaf, you could of course take off all your sills and put expanding foam into the cavity at the ledge but foam is dear and usually the plasterwork is finished OVER the sill so it's a relatively big job. Much less hassle to silicone along the gaps. For a neat finish rub your finger along the silicone after you've dipped it in some soapy water, that way the silicone (or very little) sticks to your finger and you get a smoother finish.

Let me know if you need owt else, as I have first hand experience of this (absolutely ridiculous) problem. The reason for the vents in the brickwork outside into the cavity is keep air flowing so the timber doesn't get damp or sweat. Whoever thought of timber frame houses in Ireland eh? (I imagine some bright spark from a timber frame company - cheap and easy to build)

slimjimmc

vicwatson wrote: »

Whoever thought of timber frame houses in Ireland eh? (I imagine some bright spark from a timber frame company - cheap and easy to build)

There's nothing wrong with using timber frame houses in Ireland, our climate is not in anyway extreme or unsuitable. The problem, as you've already acknowledged yourself, is poor construction standards.

vicwatson

slimjimmc wrote: »

There's nothing wrong with using timber frame houses in Ireland, our climate is not in anyway extreme or unsuitable. The problem, as you've already acknowledged yourself, is poor construction standards.

I'd go a step further and say it's poor regulation or non existence of regulation of construction standards, who are the architects that signed off off on all these buildings that were in the "poor construction" category ?

darrenheaphy

The silicon tip is a good one, I've used it too. As vicwatson wrote you can finish it quite nicely by dipping your finger in water (mixed with washing up liquid), this prevents the silicon sticking to your finger, which you can press and run against the silicon afterwards to finish it off.

Iwannahurl

vicwatson wrote: »

Yes, I know exactly what you are talking about. It's happening because the wooden window sill is placed atop the cavity and of course in that cavity there is tonnes and tonnes of air moving around (fed by the vents to the outside your house).

So, the air comes in the vents into the cavity and "leaks" into the house via the following route - think downlighters, think window sills at windows and underneath, think if plaster hasn't been completed all the way to the ground behind skirting boards, think light switches, think plug sockets, think extractor fans in kitchen and bathroom, one then also has air vents direct from outside to each room, and they want use to go green and save on our heating bills, how the hell can we do that when there is so much unnecessary air/draughts coming into timber frame houses IMO? :mad::mad:

The vents are those plastic things that protrude from the external rendering. There are also trickles vents over some of the windows. None of those stupid "hit and miss" vents or whatever they are called, which are really just big holes in the wall of your house.

God, it's all so primitive, isn't it?

I have no problem with timberframe, in general. Indeed our house is warmer and drier than many block-built houses I know, including some built under later regs. What really annoys me about this is that air infiltration massively reduces the effectiveness of insulation. We could be so much better off if these important details mattered when the house was being constructed.

With regard to air infiltration, your mentioning other possible sources is a mixed blessing! Now you have me wondering just how leaky my house might be, but at least I know where to look. I guess each problem will require its own particular solution/mitigation. Some leaks may just not be fixable.

I'll have a go at the silicon sealer around the sills.

From the list of air leaks above, which would you regard as the priorities for fixing?

gaz wac

my neighbour and I looked into getting our walls pumped. we got two companies to come a quote....third bloke was a BER inspector...told us we were told a load of cr*ap !!! only two small walls "could do with a topup" but defo not the whole house!!

but said our best best was to get expanding foam,silicone and a candle !! he said go into each room and fill EVERY single hole, crack, gap etc that you can see where the candle flickers as there is air getting in.My kitchen was always cold, but when i took the kickboard off, i noticed a 4 inch gap between floor and plasterboards...the wind was howling through it !!! Then go outside and do the same out there...tbh i havent had a chance to do it yet but my mate did and he found a huge difference !!

Iwannahurl

So 2000-year-old technology still has application in 21st Century Irish construction?

I think I might prefer to hire one of these: http://www.flir.com/cs/emea/en/view/?id=41612

vicwatson

gaz wac wrote: »

my neighbour and I looked into getting our walls pumped. we got two companies to come a quote....third bloke was a BER inspector...told us we were told a load of cr*ap !!! only two small walls "could do with a topup" but defo not the whole house!!

but said our best best was to get expanding foam,silicone and a candle !! he said go into each room and fill EVERY single hole, crack, gap etc that you can see where the candle flickers as there is air getting in.My kitchen was always cold, but when i took the kickboard off, i noticed a 4 inch gap between floor and plasterboards...the wind was howling through it !!! Then go outside and do the same out there...tbh i havent had a chance to do it yet but my mate did and he found a huge difference !!

You cannot "pump" the cavity of timber frame houses, the cavity must be there to allow the timber "breathe". You gotta be careful about going around with "expanding foam, silicone". and blocking up all and sundry, a house should have some air going through it, think the dangers of carbon monoxide if you are burning sold fuel.

Iwannahurl wrote: »

The vents are those plastic things that protrude from the external rendering. There are also trickles vents over some of the windows. None of those stupid "hit and miss" vents or whatever they are called, which are really just big holes in the wall of your house.

God, it's all so primitive, isn't it?

I have no problem with timberframe, in general. Indeed our house is warmer and drier than many block-built houses I know, including some built under later regs. What really annoys me about this is that air infiltration massively reduces the effectiveness of insulation. We could be so much better off if these important details mattered when the house was being constructed.

With regard to air infiltration, your mentioning other possible sources is a mixed blessing! Now you have me wondering just how leaky my house might be, but at least I know where to look. I guess each problem will require its own particular solution/mitigation. Some leaks may just not be fixable.

I'll have a go at the silicon sealer around the sills.

From the list of air leaks above, which would you regard as the priorities for fixing?

You can't really do anything about them all except for the sills.:( I mean, you need the extractor fans in the bathrooms and kitchen, you're hardly gonna pull off all your skirting boards to check there? downlighters would need special cups but retrofitting well...... Light switches and plug sockets....not much here either.

It is quite ridiculous though that all of these air leaks really do reduce the effectiveness of the insulation. Crazy really.

I've narrowed down the size of the air vents into the rooms (the ones up near the ceiling) by taking off the cover in the room, getting the end of a kitchen roll and putting expanding foam around it and then replacing the vent cover, it has reduced the air from outside by about 66% (I don't care what the building regs say - it's my gaf) I've done this in every room.

The low level vents around the outside of the house that allow air into the cavity - I've blocked up most of them.

Do you have an oil burner outside your back door?

Iwannahurl

Oil burner in the utility room.

No extractor fans in the bathrooms. No need either: not a patch of damp or speck of mould in ten years.

I hadn't thought of checking behind skirtings before. Now that you mention it, I ought to inspect behind the skirtings on every external wall.

Why downlighters? I have some of them in the hall, and a few on the landings (including over the stairs to an attic conversion). How does the external air infiltrate those?

Even small holes can make a big difference it seems. I had an external socket installed recently on the back wall of the house. The electrician routed the cable through from an internal socket, but didn't use any sealer. There was such a stream of cold air blowing through that I just had to seal the hole with expanding foam before the kitchen became an ice box.

Thermal Looping: http://www.passivehouseandhome.com/InsulationForPassiveHouses.html

BryanF

hi i picking up this thread, where lot of different points have been made regarding insulating of cavity and air-tightness. just to point out that thermal looping image you attach is specific to block homes and if you have a timber frame inner leaf you require this air gap, which should not behave as shown in the above image. as regards air leakage, in a timber frame house this is generally caused by a lack of continuous Vapour barrier (taped and sealed) behind the plasterboard, often in conjunction with less than adequate amounts of insulation between the timber studs. yes, foam works to a degree but its a remedial measure and one that cant get to every area as highlighted above, for instance accessing a poorly sealed ceiling void, light fittings and the worst of all dormer knee high walls/ attic conversions. From practically experience, the best method of tacking this is generally to remove the internal plasterboard in the worst effected areas and installing increased insulation and proper VB

vicwatson

Iwannahurl wrote: »

Oil burner in the utility room.

No extractor fans in the bathrooms. No need either: not a patch of damp or speck of mould in ten years.

I hadn't thought of checking behind skirtings before. Now that you mention it, I ought to inspect behind the skirtings on every external wall.

Why downlighters? I have some of them in the hall, and a few on the landings (including over the stairs to an attic conversion). How does the external air infiltrate those?

Even small holes can make a big difference it seems. I had an external socket installed recently on the back wall of the house. The electrician routed the cable through from an internal socket, but didn't use any sealer. There was such a stream of cold air blowing through that I just had to seal the hole with expanding foam before the kitchen became an ice box.

Thermal Looping: http://www.passivehouseandhome.com/InsulationForPassiveHouses.html

Ok on Oil Burner it's just if it was outside, shoddy builders have been known not to block up the area where the pipe goes into the house and this can allow a significant amount of air into the cavity.

No extractor fan in bathroom, the shower must be on an outside wall then? Access to a window? Though an extractor fan was mandatory mind?

Skirtings on external walls? Don't understand? I was referring to behind skirting boards inside the house.

Put your hand up to the downlighters when switched off and you'll know if you have a draught. The draught can occur as once the air is in the cavity from outside it tends to have free roam around it, between the ceiling and floor that are joists which tend not to have any insulation in them so the air can flow along the joists.

Yes, small holes can be worse than larger ones, you could have perhaps used silicone around the outside of the outside socket where it meets the wall, these sockets can protrude from the wall particularly if the wall has dashing on it.

Ok happy siliconing your windowsills !!

goat2

BryanF wrote: »

hi i picking up this thread, where lot of different points have been made regarding insulating of cavity and air-tightness. just to point out that thermal looping image you attach is specific to block homes and if you have a timber frame inner leaf you require this air gap, which should not behave as shown in the above image. as regards air leakage, in a timber frame house this is generally caused by a lack of continuous Vapour barrier (taped and sealed) behind the plasterboard, often in conjunction with less than adequate amounts of insulation between the timber studs. yes, foam works to a degree but its a remedial measure and one that cant get to every area as highlighted above, for instance accessing a poorly sealed ceiling void, light fittings and the worst of all dormer knee high walls/ attic conversions. From practically experience, the best method of tacking this is generally to remove the internal plasterboard in the worst effected areas and installing increased insulation and proper VB

i have a dormer, and these knee high walls have been my biggest problem, there is a gale of wind coming under the floorboards upstairs, i had to cut through the wall to see what was behind it, it was very poorly insulated, the boards that support the floor that go through the wall have a gap all around them, leaving in loads of cold air, not alone are these holes around this timber or is it beams freezing the upstairs rooms, it is also freezing the ceiling of the downstairs as well as causing draughts through plugs and windowsills on inside, it is a pure pain, i am at the moment redemying them, it is costing me a bomb, and my poor knees, shoulders and hips are suffering, trying to get through a small gap, but i swear i will not go through another christmas with the house as it is, i am also taking down those insert lights that are outside the house, and putting up lights that are below the surface of the overhang outside house,

sonofsteptoe

Hi Vicwatson, What are these downlighter cups made of and where can I source them?
Thanks

BryanF

goat2 wrote: »

i have a dormer, and these knee high walls have been my biggest problem, there is a gale of wind coming under the floorboards upstairs, i had to cut through the wall to see what was behind it, it was very poorly insulated, the boards that support the floor that go through the wall have a gap all around them, leaving in loads of cold air, not alone are these holes around this timber or is it beams freezing the upstairs rooms, it is also freezing the ceiling of the downstairs as well as causing draughts through plugs and windowsills on inside, it is a pure pain, i am at the moment redemying them, it is costing me a bomb, and my poor knees, shoulders and hips are suffering, trying to get through a small gap, but i swear i will not go through another christmas with the house as it is, i am also taking down those insert lights that are outside the house, and putting up lights that are below the surface of the overhang outside house,

your mixing up insulation and air-tightness, both need to be addressed in the right order. also please ensure that retain ventilation to the roofing felt in this zone and keep the air-tightness/vapour barrier to the inside of the insulation, taped and sealed

http://www.boards.ie/vbulletin/showthread.php?p=76076138#post76076138 here's a good link discussing this issue

BryanF

sonofsteptoe wrote: »

Hi Vicwatson, What are these downlighter cups made of and where can I source them?
Thanks

http://www.ecologicalbuildingsystems.com/products/airtight-accessories/optime-airtight-downlight-housing/

goat2

BryanF wrote: »

your mixing up insulation and air-tightness, both need to be addressed in the right order. also please ensure that retain ventilation to the roofing felt in this zone and keep the air-tightness/vapour barrier to the inside of the insulation, taped and sealed

http://www.boards.ie/vbulletin/showthread.php?p=76076138#post76076138 here's a good link discussing this issue

read the link, cannot afford new roof, so i have to go the diy plan, could not even afford to get someone else to do the job, but i will keep trying, i do find that the expanding foam does stop the draughts, in the small holes,

brendan_donegal

I am in a lucky position just about to put on my window boards.
I can see innerleaf of block work cavity and internal drylining, I can see a very small piece of the cavity about 1 cm.
What is the best thing to do before putting board on?

2 stroke

darrenheaphy wrote: »

The silicon tip is a good one, I've used it too. As vicwatson wrote you can finish it quite nicely by dipping your finger in water (mixed with washing up liquid), this prevents the silicon sticking to your finger, which you can press and run against the silicon afterwards to finish it off.

Athough I've done this myself I don't anymore. There will be some minor skin damage doing this & industrial silicone isn't the nicest thind to be getting inside your body. I suggest using a wet gloved finger or something other than your finger (not your knob:eek:).

Shinnie0503

vicwatson wrote: »

You cannot "pump" the cavity of timber frame houses, the cavity must be there to allow the timber "breathe". You gotta be careful about going around with "expanding foam, silicone". and blocking up all and sundry, a house should have some air going through it, think the dangers of carbon monoxide if you are burning sold fuel.




You can't really do anything about them all except for the sills.:( I mean, you need the extractor fans in the bathrooms and kitchen, you're hardly gonna pull off all your skirting boards to check there? downlighters would need special cups but retrofitting well...... Light switches and plug sockets....not much here either.

It is quite ridiculous though that all of these air leaks really do reduce the effectiveness of the insulation. Crazy really.

I've narrowed down the size of the air vents into the rooms (the ones up near the ceiling) by taking off the cover in the room, getting the end of a kitchen roll and putting expanding foam around it and then replacing the vent cover, it has reduced the air from outside by about 66% (I don't care what the building regs say - it's my gaf) I've done this in every room.

The low level vents around the outside of the house that allow air into the cavity - I've blocked up most of them.

Do you have an oil burner outside your back door?

Just on the blocking of these low level vents, I have a block house built 13 years ago but timber flooring was installed using the old fashioned method i.e. placed on rafters on sub-floor and we have the vents then around the whole house. The house is quite drafty in winter and as the floor boards extract, it gets worse. I have put caulk around the skirting boards blocking up the gap but was told that I shouldn't block the vents outside as my floor will rot -- could I even block some of it?

BryanF

brendan_donegal wrote: »

I am in a lucky position just about to put on my window boards.
I can see innerleaf of block work cavity and internal drylining, I can see a very small piece of the cavity about 1 cm.
What is the best thing to do before putting board on?

Air-tightness membrane sealed and taped to wall and window, cavity closer and insulation to stop the thermal bridge. How come you've a new cavity and drylining? How come you've no details or have planned how this detail will work ?

BryanF

Shinnie0503 wrote: »

Just on the blocking of these low level vents, I have a block house built 13 years ago but timber flooring was installed using the old fashioned method i.e. placed on rafters on sub-floor and we have the vents then around the whole house. The house is quite drafty in winter and as the floor boards extract, it gets worse. I have put caulk around the skirting boards blocking up the gap but was told that I shouldn't block the vents outside as my floor will rot -- could I even block some of it?

Your right to retain the ventilation to your subfloor timbers. But that's different to the requirement for background ventilation that helps keep our internal RH at low levels and the indoor air fresh.. If you have drafts from your floor this can be solved - lift the floors and install a membrane to stop air movement (this should be taped and sealed to your walls. You may as well insulate the floor while your at it.