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Friday, 22 June 2012

Partial Cavity Fill Insulation on new cavity walls

I have just been over to a community project in Cardiff to have a look at their new building (and old building that is suffering from poor workmanship and maintenance). The new building looks great, but closer inspection revealed a load of issues, but the main one was with the insulation. It is a really common fault and one that drives me mad!

The insulation was, as commonly the case with new buildings, a partial fill in a block work wall using boards. This was designed to fulfil building regs (and no more - another bug bear!) and I am sure that the drawings do fulfil the regs, however the reality will be different. Why? Two main reasons:

1. The boards were not fitted snugly together, so in some areas that I could see there was at least a centimetre gap between the boards. This will create cold spots in building that could lead to damp via condensation. It also severely affects the costs of running the building as the actual build would not meet building regs if this poor workmanship were factored in.

2. The boards that were more snugly put together (not very many from my visual inspection, as most had a 5mm gap between them) were not taped. This allows air to get behind the insulation and again negates a lot of their effect.

If you are to build an extension with these insulation boards that you really need to ensure that:

A. All boards are butted up tight against each other
B. All joints are taped using high quality tape that will last a very long time
C. All insulation is clipped back to the internal wall (this had been done in the case I looked at this AM)

Would you pay to have a cut through of a wall looking like the picture below?? Project management and attention to detail is key and so important to get what you are paying for, otherwise your newly built structure may end up being a real disappointment with much higher energy bills than you were expecting. Be warned!

Thursday, 21 June 2012

Underfloor vents - keep 'em clear

Underfloor vents are really important for the health of your home. The airflow that is facilitated keeps any excess moisture from the ground away from your floor joists, thus helping to keep them damp and rot free.

It is really common to see vents blocked by: rising paths around houses; debris from rendering; deliberate blocking to stop draughts. When the vents stop working effectively the levels of moisture can build up in the wall structure as well as creating more humid air under the suspended floor. The ends of the joists are really in trouble when this happens.

Another common problem with maintaining good air flow under suspended floors is when one or more ground floor rooms have replacement solid floors installed. This blocks the flow of air under the house / remaining suspended floor unless vents / pipes are installed into the solid floor to maintain a through draught. This is very rare indeed to see. Just having one vent at the front or back of the house is not enough to give adequate ventilation for the remaining suspended floor as certain areas develop stagnant air pockets.

So we recommend ensuring that you have a good through flow of air under any suspended floor, even if this means creating vent channels through retrofitted solid floors.

Having a draught under your house might be a good thing for the health of the building, but not so attractive for keeping the inside of the house warm, so we recommend insulating your floor using breathable insulation so that you can have a healthy and warm home during the cold and wet seasons.