How to create a 300mm overhang on a lean to tiled porch roof

benjiman · 9 Apr 2019

Hi All,

Looking for some help on a lean-to tiled porch roof.

I'd like to create a 300mm overhang on a porch roof so I can install downlights and also to accommodate external wall insulation.

If I construct this the standard way, by having a wall plate for top and wall plate at front and then creating a bird mouth for the joists to sit on the front wall plate, and leaving the required overhang, then when I come put the soffit board, fascia on, it will end up covering too much of the double glazing frame work.

I'm thinking the solution is to extend the ceiling joists out to the required 300mm, then put the roof joists from the wall plate at the back as normal, and attach the front to the ceiling joists overhang and cut off excess.

But i'm not sure if structurally this is good practice?

What other options do I have?

Thanks,

noseall · 9 Apr 2019

benjiman said:
What other options do I have?

Raise the wall plate?

Shallower pitch?

benjiman · 9 Apr 2019

noseall said:
Raise the wall plate?

Shallower pitch?

Ahh good thinking. Yes that may work! Thanks.

Notch7 · 9 Apr 2019

benjiman said:
Ahh good thinking. Yes that may work! Thanks.

If you are unsure, draw it out as a full size section on a bit of mdf, or to scale on peper.

You can then see what plumb and seat cuts you need to do.

noseall · 9 Apr 2019

benjiman said:
Ahh good thinking. Yes that may work! Thanks.

Does this roof already exist - i.e. are you modifying an existing roof?

^woody^ · 10 Apr 2019

benjiman said:
the standard way, by having a wall plate for top and wall plate at front

The standard way?

benjiman · 10 Apr 2019

noseall said:
Does this roof already exist - i.e. are you modifying an existing roof?

This is going to be a new roof.

foxhole · 10 Apr 2019

benjiman said:
Hi All,

Looking for some help on a lean-to tiled porch roof.

I'd like to create a 300mm overhang on a porch roof so I can install downlights and also to accommodate external wall insulation.

If I construct this the standard way, by having a wall plate for top and wall plate at front and then creating a bird mouth for the joists to sit on the front wall plate, and leaving the required overhang, then when I come put the soffit board, fascia on, it will end up covering too much of the double glazing frame work.

I'm thinking the solution is to extend the ceiling joists out to the required 300mm, then put the roof joists from the wall plate at the back as normal, and attach the front to the ceiling joists overhang and cut off excess.

But i'm not sure if structurally this is good practice?

What other options do I have?

Thanks,

Use leds instead only needs 20mm space .How thick is the insulation?
Extend a frame out on top of ceiling joists and run roof out to that, reduces the pitch a little .

benjiman · 10 Apr 2019

foxhole said:
Use leds instead only needs 20mm space .How thick is the insulation?
Extend a frame out on top of ceiling joists and run roof out to that, reduces the pitch a little .

Insulation is going to be 50mm thick.

If I extend a frame out from the ceiling joists, would this not be an issue structurally as usually the bird mouth sits on the wall plate above the door/window and balances out the weight of the roof?

foxhole · 10 Apr 2019

benjiman said:
Insulation is going to be 50mm thick.

If I extend a frame out from the ceiling joists, would this not be an issue structurally as usually the bird mouth sits on the wall plate above the door/window and balances out the weight of the roof?

Not from the joists , separate ladder through wall to hold end of roof joist further out .Similar to my roof over doors .

benjiman · 10 Apr 2019

foxhole said:
View attachment 162481
Not from the joists , separate ladder through wall to hold end of roof joist further out .Similar to my roof over doors .

Hmmm this sounds interesting. Just trying to figure out what you mean though! Cant quite picture it..Can you explain bit further please?

Which area do the rafters sit on the front of the roof?

catlad · 10 Apr 2019

Once the rafters come past the wall plate to the fascia which you can get away with as little as 100mm
You can then trim the rest of the rafter back its called a plancher cut its to accommodate
the soffit.

Ian H · 10 Apr 2019

Notch7 said:
to scale on peper.

Like that?

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

How to create a 300mm overhang on a lean to tiled porch roof

Similar threads