Wind through eaves of loft conversion

[namdas]

Hello!

We bought a house last year that had a loft conversion done about 20 years ago. No building regs signed off but the surveyor seemed pretty happy about it.

The issue is we've been getting terrible draughts down the stairs. I've put draught excluder around the eaves doors and the door to the loft bedroom which helps, but it does seem to me something is wrong. If I go inside the eaves on a windy day like today there is a literal cold wind blowing through. I know there is meant to be some ventilation, but this seems crazy!


We also get draughts coming *up* through the gaps in the floorboards in the loft's bedroom, so presumably they are cooling the ceiling of the rooms below too.

I'm a bit confused as to how it's insulated - there are celotex type boards below the roofing tiles, but also it seems some sort of insulation board on the exterior of the walls of the loft room and bathroom. There also was no insulation between the floor of the loft and ceiling below (I added some above the bathroom as you can see in pic, but there's none below the floorboards in the extension yet), not between the rafters in the eaves.

Presumably this makes it a 'warm roof' not a cold one?


My instinct is to go nuts with expanding foam around the sides of all the insulation boards in the roof, but I'm not sure if the eaves are supposed to be totally airtight below the roof boards, with airflow only above this insulation, or if there is still supposed to be some sort of ventilation in this sort of setup?

Is this something I can fix myself on a diy weekend, or should I be getting a professional in? I've attached a couple of photos

(the general state of the roof insulation)

(the insulation boards on the interior wall as well as the roof)

[dmsims]

That looks a really bad job (and that's coming from an amateur who has just insulated a conversion!)

Those boards should line up and be taped

The key is to find out what is between the insulation boards between the rafters and the roof

e.g.

Is there an air gap?

Is there a membrane ?

What is the external roof covering?

How old is the property ?

[Welshbeef]

OP those boards are not in place correctly. It might be wins over 20 years that’s moved them or very poor installation.


Regardless you’d want to take them off to have a look to see what’s happening behind them. (Simple with those insulation boards as they push back in.

What will you want the loft conversion to be used for? If it’s storage it can be a DIY cheap fix with the materials you have onsite. If you want it to be a living space then get it finished properly WITh building regs (I know it’s not really needed BUT when you come to sell it that official documentation removes any “negotiation room”.

[namdas]

Thanks to you both for your answers.

I just had a poke around and wasn't able to pull a board out to check behind just yet and need to pop out for a moment, but in answer to the questions:

- The house is 1930s

- There is an air gap, i knocked a board in by mistake then managed to lever it back in place, so I'm guessing at least 2 inches. Not sure on membrane until i get one out properly, i'll try in an hour or so

- Some of the boards have a little expanding foam and there a single piece of tape (unstuck) I can see that might have been used to keep a board in place, but it is irregular and not around every board

- The external roof is tiled not slate, so i guess terracotta?

- The loft itself is already converted, and has a bedroom and ensuite bathroom - the photos are of the eaves of the pitched roof. When the radiator is on the bedroom is reasonably warm when standnig, but draughty at floor level as wind pushes up through the gaps in wooden floorboard below. The space pictured will remain as storage but I would like to minimize draughts and heat loss - and if it warms up the kids bedroom below that would be a bonus


Given there's an air gap above the boards, if I can confirm a membrane too could I just whizz around with foam and tape and fill all the gaps, or should i get a professional to take a proper look

[dmsims]

To meet Buiding regs there should be an extra layer of insulation under the rafters which can also act as a vapour barrier e.g. foil boards that are taped

How thick are the current boards?

You need a continuous run of insulation and vapour barrier

[dmsims]

Having looked at the pictures again you have an insulated dwarf wall and the eaves are only used for storage ?

Is there any floor insulation in the eaves ?

[namdas]

Hi Dmsims,

Yes,that was what puzzled me - why is the dwarf wall insulated when the roof is too? The previous owners did a lot of ..interesting.. diy, so its possible the foam boards under the roof were added later?

But there is/was no floor insulation in the eaves, apart from what I added above our (freezing) bathroom last year to limited effect.

I prised out a small chunk of insulation board and it appears there is sort of sheeting behind - I've attached a picture. The boards themselves are 70mm thick and there is a 30mm air gap between them and the sheeting.

[Little Lofty]

Obviously if it’s 20 years old it won’t meet today’s regs but most of it looks wrong, and some of that timber doesn’t look 20 years old but that’s not the point. It’s difficult to tell 100% from a photo but I’d say the dwarf/ purling wall isn’t insulated, but just has foil backed plasterboard attached, the roof behind the wall doesn't need to be insulated as the wall should be, the floor area behind the wall should also be well insulated as it’s still just loft space, and the whole floor should be fire proofed to stop fire spreading from the rooms below. 20 years ago Rockwool was the only insulation needed to meet the regs so the foil board has been added at a later date I assume. The area behind the walls should be cool and draughty this time of year but that shouldn’t be coming into the habitable parts of the house.

[dmsims]

namdas said:

I prised out a small chunk of insulation board and it appears there is sort of sheeting behind - I've attached a picture. The boards themselves are 70mm thick and there is a 30mm air gap between them and the sheeting.

Is that the dwarf wall or roof?

[namdas]

Having had a better look I think Little Lofty is right - its only foil backed plasterboard on the dwarf wall, not proper insulation. There are other areas of wall that are just board with no foil too.

The photo of the insulation I pulled out was from the roof itself.

Most of the floor in the eaves is just the ceiling from below, which appears to have been sprayed with what the surveyor thought was a sort of concrete. Would this provide the fire break?

If this means I should be laying insulation on the floor, should I also be pulling up the floorboards of the attic bedroom to lay insulation there, too, given there is a wind coming up from between the boards there too? I pulled up one once to find it was just the same bare ceiling below as in the eaves.

[Gooose]

Couldn’t you just tape the insulation up and maybe board over with a thin ply, it should keep the drafts in the rafters then?

[dmsims]

You definitely want insulation on the floor in the eaves (say 100mm between the joists and 100mm cross layed - depends how deep the rafters are)

this needs to meet the dwarf wall and block the cold air

I would also spend some time taping, filling the gaps with foam on the boards in the eaves roof

[Little Lofty]

dmsims said:

namdas said:

I prised out a small chunk of insulation board and it appears there is sort of sheeting behind - I've attached a picture. The boards themselves are 70mm thick and there is a 30mm air gap between them and the sheeting.

If that is the roof it looks like mould is forming on the underside, which would indicate condensation. If there is no insulation between this space and the rooms below then the heat form those rooms is going straight through the loft eaves and through the roof, which will be causing the condensation. I’ve not seen a sprayed ‘concrete’ used In lofts for the purpose of fire regs, chicken wire and fire quilt is the norm, the ceilings may have been over boarded though?
I always wonder why lofts if done correctly have no regs, as if they are done correctly then it’s only a few hundred quid extra to get it signed off. Too late now but it’s a pity you didn’t get it checked out by a specialist before you bought the house.

[namdas]

Thanks again to everyone for their input, it's really helpful.

I'm a little concerned by the appearance of mould - though this area is directly above the bathroom where our extractor fan has been out of action and the downlights vent into the roof - which is why i was up in the attic space adding a new fan to notice the wind!

If I were to tape these boards up properly, and seal the downlights / reinstate the extractor is it likely the mould issue would settle down?

I wanted to pull out another bit of board from the other end of the attic for comparison to see if there were condensation issues there too, but they have been so well wedged in comparison to the other space I can't get them out, so perhaps they are fairly airtight too, unlike above the bathroom?

[Little Lofty]

namdas said:

Thanks again to everyone for their input, it's really helpful.

I'm a little concerned by the appearance of mould - though this area is directly above the bathroom where our extractor fan has been out of action and the downlights vent into the roof - which is why i was up in the attic space adding a new fan to notice the wind!

If I were to tape these boards up properly, and seal the downlights / reinstate the extractor is it likely the mould issue would settle down?

I wanted to pull out another bit of board from the other end of the attic for comparison to see if there were condensation issues there too, but they have been so well wedged in comparison to the other space I can't get them out, so perhaps they are fairly airtight too, unlike above the bathroom?

As mentioned you need to insulate the eaves with rockwool, this will help stop heat from the bathroom and other rooms getting onto the cold roof surface and forming condensation, the regs require 300mm, the roof should have vents in this area which also helps keep condensation at a minimum. I would aslo insulate the dwarf walls with 90mm celotex type foil board to reduce the heat entering the eaves from the loft room, it will also help keep the cold out, any hatches/doors into the eaves should also have insulation on the back. You are trying to keep the loft room as airtight as you can, but the eaves should be as unheated as possible with plenty of ventilation. It’s a crap job to do even whilst the loft is being constructed, it’s even worse once all the walls are in place, but it will be worth doing.