Matching Roofs

The ability to match existing roofs is critical in a range of situations, most often where extensions to existing structures require roof planes to line through or where there is a new build with a structure by others, steel for example. A fire damaged building where partial roof structures require replacing will also need to be matched.

Sometimes we need to match one side or in slightly more critical situations, both sides.

In instances where a customer isn’t confident or able to measure the roof, Apex Timber Engineering will carry out a site measure.

Firstly we need to ensure that the customer has made the necessary arrangements for our survey and that the new structure is far enough in the build for useful measurements to be taken. We also need access to the structural components of the existing roof which will usually include removing tiles.

“Essentially, we need to replicate the triangle that’s present on site which should be easy? Span & height = triangle. Wrong,” explains MD Mat Harbour. “That simple calculation doesn’t give allowance for the depth of timber being used.  It’s therefore critical to obtain the plumb measurement at the outside of the wallplate. Using the height, span and vertical measurement at the heel, we’re then able to create 3 points to create the correct pitch.  With the use of modern measuring equipment we can often obtain the correct pitch using a digital level however basic trigonometry is still used as a back-up check, the maths is never wrong!”

Other challenges may present themselves when matching existing roofs – older roofs may have sagged and may also have a lot smaller timber depths than we can match, creating a shallower eaves detail.  This is overcome by a ‘french heel detail’.

If you’d like to talk to our specialists about a project where matching existing roofs is a vital part of the design, email us or call 01933 510150.