INTERNAL DOORS & MVHR

In a house with a mechanical ventilation system, you need airflow from room to room to maintain a balance. The normal way to do this is to have a gap between the bottom of the door and the finished floor surface (known as the undercut) – and if you want to order standard doors, this needs to be factored in to the height of the openings.

Total Home Environment, our heat pump ventilation supplier, asks for the undercut to be 10mm. The slight challenge is that, in most cases, you won’t have a finished floor at the point you want to form the openings and order doors (just the screed or deck).

For the ground floor, we’d already selected our tiles and knew the build-up would be 17mm – so we could do the maths. But upstairs, we knew we’d be carpeting the landing and bedrooms, but hadn’t yet picked out a product.

It’s amazing how difficult it is to research a standard build-up height for a decent carpet and underlay – and neither our main contractor nor Total Home could give us a suggested figure. In the end, we took up a strip of carpet in the office and measured that up (we’ve allowed 20mm, in case you need a guide for your project).