draughts behind the drywall

[daniel.a.wilson]

Hi all,

My house was built in 2002 with a raised ground floor, air bricks every two meters and dot and dab dry lining throughout. The loft was "ready convert ed" with two rooms upstairs and a full second staircase. Sold as a 6 bed p lace but really 4 bed plus 2 loft rooms. Since moving in 3 years ago and h aving had time to poke around and get to know the place, it is now clear it was built in a hurry and to a tight budget, despite the fairly good reputa tion of the (local) house builder (company since dissolved).

My main gripe with the place is that our energy usage seems high for a new build. The crappy original gas boiler kicked the bucket last year and I re placed it with a decent one. With two of the bedrooms and one loft room le ft completely unheated a year round, and only the small office room in the loft heated occasionally, *and* being tight with the thermostat (two jumper s for everyone!) we went through 30,000 kWh of gas last year. The place ge ts cold *really* fast once the heating goes off. I think I may have found the reason...

Recently I was routing some network cables from one of the loft rooms down the behind the drywall all the way to the living room downstairs. When I c ut a hole in the plasterboard to fit a faceplate for the network point I wa s struck by a howling cold draught from the hole, which appeared to just ai r blowing from under the raised floor (at outdoor temperature) and up behin d the drywall. I lifted a floorboard in the living room near the wall unde r the network socket, pushed the mineral wool insulation to one side, and I could easily get my fingers between the plasterboard and blockwork. Its l ike the floorboards were installed a good inch away from the blocks, which seems wrong to me. Having lifted some boards immediately above this area o n the 1st floor, the draft is blowing all the way up the wall and chilling the air in the ceiling void too. I think they call this a "plasterboard te nt".

So my questions are:

1) What remedial action is recommended for preventing thermal bypass behind poorly installed D&D drywalls without ripping it all off and plastering th e blockwork ? I thought maybe drilling holes and injecting expanding foam all the way around the top of the skirting / around windows. Any better id eas ?

2) Do we risk any moisture/mould problems having taken such remedial action ? I'd have thought it would make things better if anything, as the plaste rboard wouldn't be so cold and less prone to condensation, but any thoughts on this ?

3) The survey says there's sheet insulation in the cavity and there's certa inly some visible in the roof (eaves of the loft rooms allow access). Any ideas how to establish the quality of the cavity wall insulation, in case t his is causing loss of heat ?

4) It's a big house. perhaps 30,000 kWh a year is normal even when being t ight with the heating ?

Thanks !

Dan

[Tim Watts]

That sounds like a good option - I would use fire retardant foam as you don't quite know what it's going to get up against or what's going to go wrong in the future.

Endoscope would be handy so you can see what you are about to foam up.

It's *an* option, there are probably many more.

Got any photos?

[Jonno]

Tim Watts scribbled

He'll have to be careful with expanding foam, it might well force the plasterboard off the wall.

[harry]

wo meters and dot and dab dry lining throughout. The loft was "ready conve rted" with two rooms upstairs and a full second staircase. Sold as a 6 bed place but really 4 bed plus 2 loft rooms. Since moving in 3 years ago and having had time to poke around and get to know the place, it is now clear it was built in a hurry and to a tight budget, despite the fairly good repu tation of the (local) house builder (company since dissolved).

w build. The crappy original gas boiler kicked the bucket last year and I replaced it with a decent one. With two of the bedrooms and one loft room left completely unheated a year round, and only the small office room in th e loft heated occasionally, *and* being tight with the thermostat (two jump ers for everyone!) we went through 30,000 kWh of gas last year. The place gets cold *really* fast once the heating goes off. I think I may have foun d the reason...

n the behind the drywall all the way to the living room downstairs. When I cut a hole in the plasterboard to fit a faceplate for the network point I was struck by a howling cold draught from the hole, which appeared to just air blowing from under the raised floor (at outdoor temperature) and up beh ind the drywall. I lifted a floorboard in the living room near the wall un der the network socket, pushed the mineral wool insulation to one side, and I could easily get my fingers between the plasterboard and blockwork. Its like the floorboards were installed a good inch away from the blocks, whic h seems wrong to me. Having lifted some boards immediately above this area on the 1st floor, the draft is blowing all the way up the wall and chillin g the air in the ceiling void too. I think they call this a "plasterboard tent".

nd poorly installed D&D drywalls without ripping it all off and plastering the blockwork ? I thought maybe drilling holes and injecting expanding foa m all the way around the top of the skirting / around windows. Any better ideas ?

on ? I'd have thought it would make things better if anything, as the plas terboard wouldn't be so cold and less prone to condensation, but any though ts on this ?

tainly some visible in the roof (eaves of the loft rooms allow access). An y ideas how to establish the quality of the cavity wall insulation, in case this is causing loss of heat ?

tight with the heating ?

There's a strong possibility that insulation has not been correctly install ed. It's often rushed and bodged. The slightest gap defeats the whole insulation. Sounds like your house was built by a cowboy. Unfortunately you're outside the ten year guarantee.

Maybe an infra-red camera survey would show the extent of the problem. (Ind oors and out). Needs to be done in cold weather, ie right now.

[John Rumm]

Using a "board fix" foam would solve that one...

Note there are some plastics that are dissolved by the solvent in wet foam, so take care (cables are usually ok - but try no to insulate along the length of one or you will de-rate its current carrying capacity).

[Tricky Dicky]

I would have thought some air movement behind the PB would no bad thing. Mi nd you having said that in my daughters new build to make it as airtight as possible they even siliconed the holes the cables came through in the ceil ings. Part of the commissioning process involved fixing a dirty great fan i n the front door opening to pressurise the air inside and to measure the ra te of pressure loss.

Richard

[John Rumm]

In older properties certainly. For modern boxes the mantra seems to be "build tight, ventilate right"

Indeed. New places are not (supposedly) as dependent on background circulation for controlling moisture.

[Chris French]

In message , [e-mail] writes

Hard to say, but that sounds high for the house.

We have a bit of a rambling Victorian house, L shaped with a lot of external walls, single glazed windows, etc etc. gas consumption is

40,000 + kWh.

[John Rumm]

Indeed, just looking at my estimate from EDF, they are suggesting

27,000kWh/year for this place - solid wall, Victorian construction, exposed location, not that well insulated yet.

[News]

In message , [e-mail] writes

Google tells me 30,000 kWh in oil terms is 3,000 litres. We use twice that in a year, heating a large Victorian house with solid granite walls. The house is zoned, so we rarely heat upstairs during the day, and have minimal heat in rooms we don't use, but we're retired, so heating is on all day and, being in Aberdeenshire, heating is used most of the year.

The good news? Heating oil is comparatively cheap at the moment.

[Mike Tomlinson]

En el artículo , News escribió:

With the way things are going, it might be an idea to install a second talk and fill 'er up while the price is low. There are rumblings about restricting output which will drive the price back up.

[News]

In message , Mike Tomlinson writes

Funnily enough, that thought has crossed my mind, but I think current regs mean that any additional storage will require bunding as well as a proper base, which adds to the cost, even if DIY. We use a lot of oil, so an additional tank would have to be huge to reap any real benefit.

We joined a local oil club a few months ago which, coupled with lower prices, has reduced our costs.

[ss]

I am in an 1500 sq foot (147 sq metres) (internal) detached house.

4 bedrooms, 2 floors. Built late 70s (central Scotland) 15 radiators Estimated gas usage 14330 kWh for the year. House occupied 24/7

[harry]

Get hold of 45 gall oil drums. You also need storage and a hand transfer pu mp. OR You might get a tank second hand, my neighbour has just gone from oil to ga s.

[harry]

My total energy benefit is £4000 year. What are you people thinking of? I export 5000Kwh (Estimated) of electricty/year.

[News]

This house is detached, although I've no idea of the area, internal or external. Googling suggests there is no standard way of arriving at figures.

6 bedrooms, 3 floors

Built mid 80s (1880s), Aberdeenshire

33 radiators

Oil averages 6000 litres pa, or 60,000 kWh.

Our 'year end' is Sept. Max usage was 7479 litres, 2008/09, and min

5514 2010/11. Interestingly, oil was 16.3 ppl in 2003, hitting a high of 75.78 ppl in 2013, and 26.9 ppl earlier this month. Add VAT and it makes one hell of a difference.

Ditto.

[DICEGEORGE]

on a cold day use an infra red gun to suss where the biggest heat leaks are.

[ss]

I got one on ebay for around £9 and it appears to be reasonably accurate. Different brand though.

[News]

In message , jim writes

Sorry. Perhaps I should have said even more of a difference, with the VAT. Take our usual delivery of, say, 1000 litres. £757.80 in 2013, and £269.00 this year, a difference of £488.80. Add VAT and the figures are £795.69 and £282.45, a difference of £513.24, nearly twenty quid more. Multiply that by six, our average annual consumption, and the total saving today against 2013 becomes £3079.44, which is one hellava figure. Obviously, the figure for 2013 was not constant throughout the year, but neither will the price this year be constant.