18.7 deg pitch roof

[billm]

I am building a small extension to my house and now have the Pole and Wall plates in position. I have temporarily dropped a Rafter on and the Pitch is 18.7 deg according to the App on my phone.

I will be using a smooth Marley Modern or similar tile which are OK down to 17.5 deg with 100mm headlap.

I have notched the Pole plate end of the Rafter by just 23 % to get as much height there as possible, and the Pole plate is as high as it can go on the wall. So if possible I am looking at ways of dropping the Wall plate end of the Rafter to give more Pitch.

Although 18.7 is within tolerance for the tiles I am wondering if I can get more pitch by fastening the Rafters flush to the wall plate with joist hangers instead of cutting a Birdsmouth and running them over the wall plate. I am not having Soffits so the Fascia board will be flush with the wall in any case.

Is this possible and if so how will I hang the first row of tiles, ie batten direct on the wall plate ?

Or should I just stick with 18.7 degrees ?

thanks

 

[catlad]

I should stick with what you have a domestic extension must be a small rafter length.

 

[billm]

Yes it's only 3m long so rafter length is about 3.5m

 

[noseall]

I am not having Soffits so the Fascia board will be flush with the wall in any case.

 

[^woody^]

If you drop the wallplate then you are lowering the ceiling, so why would you want to do that?

You'll have difficulty working to fractions of degrees with your app and timber rafters too.

 

[jontop]

In theory the first course batten will be something like 12" up the rafter anyway so you should still be able to fix conventionally.

 

[billm]

Jontop, that's what I was thinking, and using hangers will give a sound wall plate connection.

I'll have a look at the headroom and see how much it will affect it

thanks

 

[^woody^]

using hangers will give a sound wall plate connection.

I doubt it. Neither will they tie the wall.

 

[billm]

using hangers will give a sound wall plate connection.

I doubt it. Neither will they tie the wall.

I don't understand, why?

 

[^woody^]

Part of the function of rafters is to restrain the wall. Hangers are no good for this, they are for vertical loads only

 

[billm]

OK thanks, I can see that now, in that case I'll cut a bigger Birdsmouth, say 50%, and use hangers to assist with supporting the weight.

I live by the coast, so it can be windy. Should I nail all the tiles down or every other row ?

Also, I noticed that on a neighbours newly built tiled pitch roof extension, looking across I can see that the tiles by the gable ends are slightly higher than the other tiles, in fact the tiles undulate a bit as they go across the rafters. He used cement packed verges not dry verges.

Is this done this to keep water away from the gable edge or is that he just didn't get all the rafters level ?

 

[noseall]

It's probably more to do with the cloak just lifting the tile batten a wee bit and the tile not being pushed fully home into mortar.