Porch roof

[greengrass]

with out harping on what I am doing has anyone any idea how to gauge the length of a rafter set at 35deg on my proposed porch roof, and where the birdsmouth should be cut along the rafter. Depth of porch 1m from house to outside porch wall. Or will the rafter measure be an on site job?
The tiles will be interlocking with min pitch of 35deg.

thanks in anticipation Greengrass

 

[masona]

I've done a loads of roofing but how to explain it is the hardest bit but I shall try, do this on the ground to get your template pattern,

If you're using 100mm x 50mm timber, make a 90 degree L shape for the rise & run, you will need to know the from back wall measurement to the front edge of the wallplate which is known as "run" to the front edge of the wallplate, see drawing and the reference line is 1/3 of the width of the timber which is 33mm maximum of the 100mm width and no more than that and draw the reference line on the timber and line it up to the top edge of the wallplate then use a protractor or a roofing square to get the 35 degree angle so this will give you the height of the roof, then use a sliding bevel to get the top angle of the rafter and tranfer it down to get the plumb line of the birdmouth, I don't know if I've explained it properly, if not, I see if I can find a link

 

[noseall]

we tend to leave the foot of the rafter elongated and cut it off later using a string line. this way you can accurately measure off the brickwork to create a uniform parallel soffit.

this is in case there are any deviations in the wall plate or pitching plate levels, relative to the brickwork.

 

[greengrass]

with out harping on what I am doing has anyone any idea how to gauge the length of a rafter set at 35deg on my proposed porch roof, and where the birdsmouth should be cut along the rafter. Depth of porch 1m from house to outside porch wall. Or will the rafter measure be an on site job?
The tiles will be interlocking with min pitch of 35deg.

thanks in anticipation Greengrass

Many thanks to you both it's going to make the job easier.

 

[greengrass]

I'm, in need of more help!!!!!!!


I hope masona and noseall are reading this. Just checking I've followed your instructions correctly rather than c....up good 100 x 50 timber by cutting the ends and bridsmouth wrong. Good one noseall I would have cut them as I made them and probably ended up with an uneven facia.

Following your instructions I have manufactued [big word] a template rafter from scrap 50 x25 to give length, and a piece of 100mm ply with the bridsmouth cut in 1/3rd to represent the true width of rafter and then slide bolted it to the 50 x 25 so I can slide it to required position on wall plate.

Offering it on to a wall plate on a couple of blocks that rep: the porch wall and fixing a scrap on the top end of the rafter [35deg] to rep the ridge board. I marked the mock porch wall height on the garage wall and measured from that line to the top of the template rafter & ridge board and came up with a measurement of 93cm, does this sound right.??

The measurement was based on the outside of the porch wall being 1mt from the house wall and obviously with the wall plate set level with the inner section of the mock porch wall. Christ I do go on but it's the only way I can describe it.

Thanks Greengrass.

 

[noseall]

instructions based on a lean-to type roof:

once you have fitted the wall plate, it's just a case of cutting one end of a 1.5m length of 100x50mm timber at 35 deg.

this timber 'rafter' is then offered up to the wall and rested on the wall plate. it will be considered at the right pitch when the 35 deg cut is sitting snug against the wall. just maneuver the timber 'till there are no gaps at the 35 deg cut.

you then use a level to mark the outer upright face of the wall plate onto the rafter and decide how deep you want your birds mouth to be. it is usually about 30mm.

cut out the b.m. and try it in place. if it's a go'er use it as a template for the rest of the rafters.

 

[greengrass]

Many thanks noseall have set it out again and came back with the same height measurement ( 93cm ) so it must be right!

I am looking on the marley and redland sites to find if there are tiles near matching that I can use at a lower angle if poss as the 35deg is a bit of a sore thumb, on paper anyway.

 

[masona]

greengrass, are you still having problem?

Edit: didn't see your post above

 

[noseall]

most of marley's interlocking concrete tiles will cope with pitches as low as 30 degrees, with the smooth versions coping with 22.5-25 degrees.

bold roll, wessex and moderns, down to 17.5 degrees or even less (wessex will cope with 15 degrees).

 

[greengrass]

greengrass, are you still having problem?

Edit: didn't see your post above

ok now think I've got it all thanks alot
greengrass

 

[greengrass]

most of marley's interlocking concrete tiles will cope with pitches as low as 30 degrees, with the smooth versions coping with 22.5-25 degrees.

bold roll, wessex and moderns, down to 17.5 degrees or even less (wessex will cope with 15 degrees).

Many thanks will check out their styles
Greengrass.