Draught Problem With Dormer Type 3 Bed Semi

Hi everyone I'm new to this forum so any help will be gratefully received.

We're in the process of renovating our first home that is a 60's, two story, dormer type type 3 bedroom semi that we purchased last summer.

We've had it rewired & a new central heating system installed so some of the upstairs boards have been removed, we've also recently had it decorated throughout .

My problems are when you put your hands down by the skirting board at the bottom of the upstairs stud walls you can feel a terrible draught coming through the dormer cheek. On windy days you can even feel gusts of winds. On further investigation I lifted a board near as possible to the stud wall & was amazed to find that where the downstairs wall (dwarf?) wall meets the upstairs stud wall there are in places two courses of bricks missing in the upstairs floor void. I also read on another forum that with the current building regs this floor void should be airtight. As a temporary measure I've wedged Rockwool pieces between the joists & between the downstairs ceiling & upstairs floorboards in the 3 bedrooms. This has made it much better where it's been done in the 3 bedrooms but it's still blowing a gale through the bathroom floor as I've not got access to it yet. I didn't realise these houses were so draughty & poorly insulated.

My questions are:

1. What would be the best way to permanently cure this problem? Would it be possible do you think to get a builder to take off the soffits outside & then if possible replace the missing courses of bricks up to the stud wall? The distance between the joists in most places is about 16".

2. Is there a way of insulating the stud Walls from the outside or the dormer cheek as I would be reluctant to remove the plasterboard from the inside as we've had it recently decorated? If so how could this be done on this type of house.

Thanks for reading.

so you 'renovated' and decorated it before you insulated or dealt with air-tightness?

1. the best way would be to lift the tiles and achieve more air-tightness from the outside especially in a dormer bungalow. missing bricks? there 'missing' for a reason you have a cold roof system which requires air-movement to circulate your roof to stop it getting damp or lead to structural problems
2. yes but this deals with insulation not air-tightness

can i just add (this is not a reflection/or dig at you) please consider air-tightness, insulation, ventilation First. ie deal with building fabric first before the heating system. and heating system BEFORE you decorate or spend money on elsewhere on your fixtures & finishes

Thanks for your reply lowCO2design.

This is my first house & as you've probably already guessed I'm no expert in house renovation so have made mistakes in what I've already done.

Yes I think it is a cold roof system but would this mean that the upstairs floor void should not be sealed??

What would the best way to insulate the dormer stud wall that sits in the roof void??

If I was to seek further advice on this what type of person should I get advice from??

Thanks again for your reply.

TheBag said:

Thanks for your reply lowCO2design.

This is my first house & as you've probably already guessed I'm no expert in house renovation so have made mistakes in what I've already done.

1. Yes I think it is a cold roof system but would this mean that the upstairs floor void should not be sealed??
2. What would the best way to insulate the dormer stud wall that sits in the roof void??
3. If I was to seek further advice on this what type of person should I get advice from??

Thanks again for your reply.

Click to expand...

1. no the floor void can be sealed but it cant be done in the way you have explained above. the best way to do it would be externally by lifting/removing the last few rows of tiles and installing/sealing the floor junction but at the same time dealing with the wall insulation general air-tightness work and install of proprietary vents for the cold roof structure. or you could go with the internal option which answers your next question but messes up your premature decoration
2. Take down the plaster board, install insulation and an air-tightness membrane.
3. Arch or arch tech with BER and Passive house experience to prepare details and specification for any tradesmen to price then ensure that said works are carried out as per the specification and materials IAB certification and building regulations. IMO an air-tightness specialist is also needed and that's best done in 2 stages ie before and after the renovation process, on larger refurbs there is no reason why a performance clause cannot be part of the contract with your builder to ensure you get the air=-tightness result you require

Thanks again for your reply lowCO2design.

I'll look more into this tomorrow pm as I've got a 4:15am start at work

In a earlier post you said that the bricks were missing for a reason to help air circulate. The roof needs ventilation but does the floor void??

If this property was to be built today would the floor void be sealed with current regs?? Is it that the building regs then would of required it to be ventilated & now there's a different line of thinking that the floor void is best sealed & no other obvious change?? Obviously I don't want to make any more big mistakes that I'll regret in the future.

I would like to post some photos but don't yet have enough posts.

Thanks again.

new roofing methods mean, that now breathable felts are used and roof spaces do not need ventilation. i doubt you have breathable felt.. in your case, while it is possible and appropriate to seal the floor void, your intiail approach worried me and i felt it necessary to explain that you will probably not be able to solve all your air-tightness issues in that area by simply taking down the soffit and putting in bricks

why not look at [broken link removed], maybe its similar to your situation...

TheBag said:

In a earlier post you said that the bricks were missing for a reason to help air circulate. The roof needs ventilation but does the floor void??

If this property was to be built today would the floor void be sealed with current regs?? Is it that the building regs then would of required it to be ventilated & now there's a different line of thinking that the floor void is best sealed & no other obvious change?? Obviously I don't want to make any more big mistakes that I'll regret in the future.

I would like to post some photos but don't yet have enough posts.

Thanks again.

Click to expand...

There is no requirement to have the first floor ventilated. Unfortunately when builders put up the first floor joists they just infill between the joist with some part blocks on the inner leaf side.

Requirements now call for making all these joint intersections between joists and blockwork airtight, in other words no air coming in from the cavity.

In 2005 my brother built a house by direct labour and I did likewise, mirro image. One month ago we went around sealing all the draughts etc. He noticed a draft coming in from 1st floor level. It was coming infrom the outside via under a rear door where the cavity was still open due to the footpath not being put down 6 years later.

Anyway my house has been on hold since, but when I popped in and saw loads of gaps between first floor joists and the blockwork on the inner leaf, then I knew he probably had the same issue on his completed house. Sealed up the cavity with expanded foam has helped, but we both know that it is not airtight like the following detail I eventually found, which I will use when I get a chance to complete my house. This is an acceptable detail now in 2009 but in 2005 if you asked a builder to do it he would have looked at you, thinking you were a bit crazy.

See pages 25 and 26

http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,18749,en.pdf

conc blocks are not air-tight and need a plaster/skim coat at least. its desperate to see the DOE showing 'acceptable' details with duct tape..