For me these were -- can we generate a list then do a vote?

1. Cavity walls

2. Blob and dob

3. Aerated concrete

4 ? Too little insulation

5 not building air tightly

6. cement mortar

7. too deep foundations

8. uninsulated suspended floors

9. Roof trusses

Can you add any more

No but you have -- thanks

? Believing that access to the right materials will mean the job will be done right? (I'm thinking particularly of insulation and incorrect detailing, but there must be hundreds of instances).

Nice ones BrianR -- thanks

I am hoping that we can develop a list and pick ten from it by voting.

James I am not saying that it is third worst just that it was a disaster -- cracks too easily, combines insulation and structure ( this is a fundamental error ) removes thermal mass and results in patchy insulation when combined with mortar, lintels and all too commonly bricks.

planning greed, if you want to build a mansion in green a field location its OK ( its not what you know its who) if you want to build a green,permacultural, modest home, then no chance.

tom

p.s fully agree with ALL BrianR and Tony's points.

ludite,

I think you misread my post

tom

Airtightness can be OK and you still can have outside air rushing arround behind the blob and dobbed boards = very high heat loss at this time of year like living in a plasterboard tent!

can anyone educate me what is wrong with cavity walls, foundations too deep and roof trusses?

The creeping nonsense that is the planning system. Having arrived at this point by many tiny steps of well meaning it is truly atrocious.

Killing off of rural development.

National guidelines for sustainability that have no relevance on the local level - for instance water restrictions in areas where supply is simply not an issue.

The concept of an entirely rigid, inflexible structure for a home (cf. deep foundations).

The preference for room numbers over practical room sizes promoted by big developers and now accepted as the norm by home owners.

British plumbing.

Using second derivatives of carbon counting as a means to measure how sustainable a home is.

Blanket application of micro-renewables.

The abysmally run, ineffectual and ultimately pointless grant system for microgeneration - which has had not one measurable effect on either the price established technologies (solar thermal) nor the uptake of new technologies such as biomass heating.

They are in house cooling systems

Probably not but that could depend on the airtightness of the cavity.

Re cavity walls -- I am saying that too much heat is lost through them. Even when filled with insulation there is still too much heat loss.

Bottom line worst case is a ventilated cavity and worse than a solid wall yes.

Had we not gone down the cavity walls route we would be much better insulated and less air leaky.

cavity walls (still) -

am i naive to believe the u-values that have been measured? - i'm sure the experiments have been done many times.

i know brickies don't fill the joints properly but the outside face should be good and reasonably air-tight.

i have solid walls and they do feel cold although they are well-pointed on the outside and plenty of plaster on the inside.

also the cavity performs the important function of interrupting the flow of water into the wall. the insulation value of the masonry will be higher, the dryer it is.

i am genuinely surprised to hear that cavity walls are seen to be worse, i can't see that anyone had a vested interest in introducing them if they were.

Cavity walls give you problems like this: http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2896&page=1#Item_3 that you can't see. Same objection with blob and dob, there is no way to tell if it is good or bad until winter and the gas bill comes...

Edited: Sorry, got the link wrong.