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Forum topic by momuzik posted 01-24-2022 04:32 PM 353 views 0 times favorited 8 replies Add to Favorites Watch
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momuzik

4 posts in 123 days


01-24-2022 04:32 PM

Topic tags/keywords: rafter

new to the world of wood building construction, been a mechanic all my life but now as a homeowner looking at improvements. wanting to construct an extension to the side of my house (I believe its called rafters). basically using 2×4’s to construct…can anyone assist in letting me know what angle I should be cutting the top of this 12in vertical of this corner? thanks in advance


8 replies so far

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MrUnix

9000 posts in 3658 days


#1 posted 01-24-2022 04:38 PM

Right angle triangle math says ~87.14 degrees. But the easy way is to just place the 2x in place and then use a scribe to mark the angle on the upright – no measuring needed.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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controlfreak

3747 posts in 1061 days


#2 posted 01-24-2022 04:40 PM

Not sure what you are attempting here but normally a straight double plate would span the width and a birds mouth would be notched into the rafters to match the top plate. Two things come to mind 1) 20’ is a really long span for a 2×4 and 2) a 20’ 2×4 is really long if they even exist. You may need a truss type of design to make this work if this is a roof line.

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momuzik

4 posts in 123 days


#3 posted 01-24-2022 05:10 PM

ok thanks guys, i will try my best

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CommonJoe

30 posts in 382 days


#4 posted 01-24-2022 05:38 PM

1.2 degrees if you take into account the width of the 2×4’s at the short end at the right.

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momuzik

4 posts in 123 days


#5 posted 01-24-2022 06:31 PM

OK thanks Joe

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Lazyman

9602 posts in 2847 days


#6 posted 01-25-2022 04:26 AM

I am not an expert but that also seems like really low pitch for a roof. If I remember correctly, an asphalt shingle roof for example, should have a 2” rise for every foot so for a 20’ run that would be 40”. Even a 1” rise would be 20”. Also, I think that the maximum span for a 2×4 for roof rafter is something like 6 or 7 feet with 16” spacing?

For better information, it might be a good idea to explain exactly what you trying to do and have some of the experts (again, I am not one one of them) point you in the right direction so that you don’t have an expensive and dangerous mistake. Also, you may need to get a building permit and submit a design and follow your local building code.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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Lazyman

9602 posts in 2847 days


#7 posted 01-25-2022 04:27 AM

Deleted double post

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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sunnybob

145 posts in 225 days


#8 posted 01-25-2022 10:35 AM

You need building advice. Those rafters are nearly 30 ft long. if thats wood, they WILL sag, a LOT!

As said above, the angle is too shallow for any kind of weather protection. If youre putting roof tiles on top then the tiles will actually be flat, allowing all the rain to go straight underneath. plus the weight of the tiles will bring the whole thing down.

Find a local expert and get him to quote for a proper and safe extension as per your local building laws Then you can decide if you can save enough money to do it yourself.

-- my projects can be seen at www.pbase.com/sunnybob

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