Ask the experts

1.How can we meet building control’s airtightness requirements?

We finished a self-build last year and we’re only now getting round to applying for a completion certificate. Building control requires a Q50 airtightness result between 5 and 7. Our test has come in at a much better 2.79 – which we’re told is too good! I’ve been informed that it’s not as simple as just inserting a couple of vents and that we may have to strip plasterboard from the walls and remove the seals from the joins between the walls and floor. In the house plans, the SAP calculations state a figure of 7 for the Q50. Unfortunately, due to disputes, we parted ways with the architect before the end of the project. Do you know of a less drastic way of getting the Q50 figure up to 5?

I’ll confess that this sort of situation is new to me and I’ve had to ask my professional contacts for their take on it. It seems a real shame to have to take retrograde action when a house has been built to such impressive standards, but it points out the perils of working to high levels of airtightness without professional guidance. I’m wondering if parting with your designer at a crucial stage has led to this situation, because no architect I know would have sanctioned building to this standard without specifying a mechanical ventilation and heat recovery (MVHR) system to maintain the levels of fresh air required inside the home. As you have no doubt discovered, retrospectively installing MVHR is expensive and disruptive, which is why it needs to be considered during the early design stages. My building control friend Paul Kalbskopf has suggested discussing the possibility of installing stand-alone units with building control.

2.Can I move my neighbour’s electricity supply?

I recently bought a steading (with planning permission to convert it to a house) and I need to re-route my neighbour’s electricity supply, which currently runs over the top of the building. Previously, both our properties were under joint ownership, before being sold off. I contacted SSE and they quoted £7,500 to bury the cable. Do I have any legal ammunition in my favour that I can use to persuade my neighbour to bear some of the cost?

I am afraid that this enquiry is most suited to a lawyer, as you are questioning the right of your neighbour to have electric cables running above your property. My own view is that, if this was being proposed now, you would have every right to prevent your neighbour from negotiating an overhead supply across your land to service their dwelling. However, you have recently acquired the steading with the overhead line already in position. One would assume that consent must have been agreed as a result of both properties being in common ownership. I would suggest that you have no right of recovery for the cost of moving these services underground but you may be able to appeal to the good nature of your neighbour for a contribution. My own experience with utility companies is that their fees are generally negotiable and if you feel their quoted sum is too high, I would tackle the matter directly with them as it may lead to a reduction.

3.What’s the best way to appeal a planning refusal?

We’ve recently had our planning application denied. We disagree with the reasons the council gave and are hoping to appeal the decision. Has anyone had any experience with appeal companies? Is it best to go with a business that uses town planners or a law firm that specialises in this area?

It is advisable to seek professional advice with an appeal, as it is very much the option of last resort. Who is best to go to depends on the nature of the case, but generally planning lawyers come into their own where the issues are complex and not ease like putting a baby in a double stroller for infant and toddler and there are legal matters to consider. For most appeals concerning new dwellings, or alterations to existing ones, consultants (who may be chartered town planners or planning and development surveyors) are the best choice and would generally be a less expensive option.

4.How do I ensure the eaves of our home are sufficiently airtight?

We’re self-building a timber frame house. The roof and tiles are now on and we’re bricking up the exterior. My brickie advised me to put an expanding foam strip between the top course of bricks and the soffit (at a cost of around £500), as this allows for the timber frame to settle. Could I get away with just pointing the junction instead?

Your bricklayer is giving you good advice for a typical softwood (open or closed panel) timber frame. I spoke to Simon Orrells at Frame Technologies ( and he confirmed that you can expect 5-6mm of settlement per storey on a timber frame structure over the first few years, so a 10-20mm thick expanding foam strip would be required. A specialist tape such as Compriband should be used. I’m afraid it is not cheap at around £5 per metre but it is self-adhesive and very easy to lay, so there shouldn’t be a huge labour cost attached. I don’t know the size of your project, so I can’t say if £500 is a fair price or not, but it doesn’t sound too far off the mark. Work out a sensible price based on the perimeter of your walls and allow for a couple of hours of labour to apply the tape. I also spoke to Oakwrights ( and they confirmed that if you are using an oak frame with infill panels, they would employ expanding foam seals. Tese are installed as the structure is erected and are included as part of their package

Plumbing and Period Homes

Mains utilities supplies are relatively new in the grand scheme of things, and the majority of older houses were built without bathrooms, running water or plumbed-in waste. What’s more, warmth was provided via open fires rather than modern boilers and other tech. So any refurbishment is likely to involve making significant upgrades to the plumbing […]

Insulating a new masonry home

Although there is a great deal of current debate about Building Regulations not changing fast enough to keep up with modern efficiency demands, the rules regarding external wall insulation are an exception. Gone are the days of simply picking an outer brick and an inner block and adding in some arbitrary cavity insulation; today, the process is a fine (and very calculated) art.

Cavity wall principles

Having two layers of brickwork with a space between them is known as cavity wall construction. This method was first introduced in the early 20th century as a way to provide better protection against penetrative damp and to help keep the inside of walls dry, so you can keep your funiture like your wooden shelf or best rated mattress dried without worrying them getting wet.

Dense concrete blocks started to be used for inner cavity layers after the Second World War, with lighter weight blocks (with air insulation) introduced in the 1960s and 1970s. A decade later and insulation started to be introduced into the cavities.