Bungalow extension, ridge beam, matching existing roof line

[Mr Chibs]

Hi all


Helping a mate build an extension to his bungalow

The bungalow has a trussed roof.
The extension (full width) at the back will have vaulted roof and patio/bifold doors overlooking the garden.

How do you pro's work out where the ridge beam will sit, so that the extension will have the same roof line & angle as the current roof?

New roof will be a cut roof.

Thanks

 

[Deleted member 174758]

If you want the same pitch and the same ridge height then the width of the extension will need to be identical to the depth (front top rear) of the existing building. I'm assuming that the revised building will have a T-form when completed

 

[^woody^]

Presumably the plan monkey was shiite then and did not annotate the dimensions on the drawing?

If it's a gable, us pro's would build the gable and then the ridge sits at the apex

 

[Mr Chibs]

Plan monkey has given very scant detail.

I realise the ridge beam sits at the apex, don’t think I explained Properly what I wanted advice about.

Say the timber size will be 225 deep for the new vaulted roof, how do I ensure that When birds mouthed etc, this will be at the same height as the current truss roof timbers?

Obviously I want to cut down on work, but If the ridge beam is sat a bit low, presume i could cut firing strips to go on new rafters to meet trusses roofline.


Sorry don’t understand T-form

 

[^woody^]

You'll know the centre of the extension, and the plate height (rafter height at the wall plate), therefore be able to set up two template rafters at the gable and these will give you the ridge height.

 

[noseall]

As per Woody really. Set up a pair of dummy rafters complete with B/M cut outs. You can even slot in a short temporary piece of wall plate into the B/M cut to determine the height of the masonry. Same with the ridge beam.

when I set up this roof....

Vaulta2

• noseall
• 6 Feb 2022

Vaulta3

• noseall
• 6 Feb 2022

Vaulta1

• noseall
• 6 Feb 2022

I had to faff about trial and erroring my way through with dummy purlins and rafters until I had the pitch, wall plate, ridge beam and purlins all worked out.

 

[Mr Chibs]

Thanks chaps.

I see there may be a little trial and error to get things going.