How do I fix draft and insulation problems in my new build home?

Q: “I’ve bought a new home and while most of the rooms are cosy, my daughter’s room at the top of the house is a good few degrees colder than any other room. How do I identify draft and insulation problems in my new build home and how do I get the developer to take it seriously?”


Clearly, something is wrong here, you should not be having draft and insulation problems in your new build home.  Any new build should be energy efficient throughout and must have an energy efficient rating of at least ‘C’ (rates are between A and G). Therefore, the house should be well insulated and pretty air tight from top to bottom. Consequently, there is no reason why the temperature is a good few degrees colder at the top of the house.

I will make the assumption that we’re talking about a problem which relates to your home during the winter period, when the outside temperature is typically 8 degrees centigrade or lower and approximately 20 on the inside when you’re at home.

First, check the radiators are all working correctly in the bedroom and make sure there is no trapped air (which could be reducing the performance of the radiator). Check online to find out how to bleed a radiator or call a plumber if necessary.

Next, check if there is a loft hatch door in the bedroom, and if so peek inside to see if the space above is well insulated and the loft hatch door is also well sealed and draught-proofed.

Have a look at the NHBC book that came with the house, as it should say what type of insulation, wall, loft and floor construction the house is made of. This is helpful for you to know.

Next, check for air gaps around the window frames and ceiling corners, and then work your way around the skirting boards feeling for gaps. Do this on a windy day.

Now, assuming you have done all of the above and this bedroom is still cold, the next theory is that the hot air warmed by the heating system rising up to the top bedroom is escaping.  The question is where and why?

In a typical house, there are hundreds of gaps and cracks that provide passageways for warm air to escape. Examples are holes for recessed ceiling lights, gaps around the loft door, service points, wall cavities, joist ends etc.

What’s happening here is also known as the Stack Effect. Basically, escaping air creates negative pressure inside the house (especially in the winter months) – creating a vacuum that causes air infiltration. The warm air that’s escaping from the top is being replaced by cold air entering from the ground and then working its way up again.

Since 2006, Building Regulations in England and Wales have required mandatory air leakage testing of new homes. The test provides a measure of the amount of uncontrolled air leakage taking place from the home. Ask your house builder to see a copy of this test and the results. While this will only provide you with the rate of air change, you can ask the following question to your builder: “Would you expect to feel lots of drafts from a house which has been tested?”

If the problem remains, then you need to start checking what’s going on with the insulation. The easiest way is to start poking the walls in different areas and/or check behind electrical outlets (all power turned off first) and see if you’ve got insulation where you think you should have.

Alternatively, ask the builder if they would be happy to pay to have your house re-assessed using a blower door in conjunction with thermal imaging. The use of a blower door in conjunction with a thermal imaging camera to record the images is the most effective way to bring hidden problems to life (a blower door is simply fitted to your front door and has a large fan).

Similar to the air pressure test, a blower door is used to gently suck air from your home. The whole purpose of this approach is to get the air moving within the building so we can start to identify all the invisible draughts, plus any ‘potential’ missing or patchy insulation.

All of this will invariably affect the thermal performance of your home. IR (Infrared) images can then be taken to record the temperature differences from one room to the next. If the camera is displaying a range of colour patterns (where red is warmer and blue is colder) across an internal wall or ceiling area, it’s a clear indication things are not as they should be. Ideally you should see a consistent colour pattern within a given area.  Studies have shown that if 10% of insulation is missing, it typically reduces that part of the building’s ability to retain heat by a staggering 50%.

Whilst an IR (Infrared) survey with blower door is quite expensive (prices can start from around £250), it will instantly show you what’s happening within your home. In your case, if a survey reveals large amounts of blue (cold draughts) in areas where they shouldn’t be (skirting boards, windows, stairways, cracks etc) and poor insulation (images showing a range of different colour patterns and uneven temperatures), then it provides compelling evidence that the house is not as air tight as it should be and/or the insulation installed is not doing it’s job correctly by retaining the heat in a consistent manner. As they say, a picture is worth a thousand words.


Answered by Steve Perris, IR Heat Mapping


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