Repairing a roofing structure on a shed style roof
So I am having a bit of an issue with a shed style roof on a 10×12 shed I built to model after my home. I leveled the base put down 2.5 tons of rock down then 4 railroad ties lifted the subbase 2x6x12 on 1.5″ OSB doubled with walls 2x4x80″ 16o.c. Pitch only 5/6. Remember modeling after my home. Where I messed up is using 2x4x14 on 24o.c. on 3 and a 30″ gap on 1. I am almost done by I have noticed that I have 2 low spots in the roof after I have shingled 90% of it. Hind site I should not have cheaped myself and use 2x6x14.
What’s the best way and easiest to Fix the 2 low spots so water does not pond on me? In the framework that is already cross braced. Door opening 65″ with a 2 steel bed frames angle brackets used on both sides for the 2×4 overhead the door opening as a lental.Even though my pitch is high enough but not much. I do have 2 rolls of paper #15 and architectural grade shingles installed.
One of the spots I kind of fixed by added 2 layers on shingles there to level out that spot. But the other low spot with the larger 30″o.c. spanned concerns me a litle bit.
Thanks in advance,
Tim
Replies
You do have a problem. 2x4's are too small for the span. I would roll in several more 2x6" rafters into the spaces between what you have now. It looks like you have the existing rafters sitting on posts so after the new rafters are in you should but a 2x6" beam across the posts to provide the support the new rafters will need.
Gravity is insidious and will eventually pull the middle down if you don't provide more support.
One thing you could do is sister a 2x6 to each of the 2x4 ceiling joist. Take the sag out of the 2x4's with the 2x6's. You will lose a couple of inches of ceiling height.
The sistered 2x6's need not bear on the walls. The shear value of the 2x4's is adequate for the roof loads. Cut the 2x6's to the length of the distance between the front and back walls.
It may get a little complicated when start finishing the inside. May have to do some blocking and stuff.
Just a thought.
With such a low slope roof, water will work its way under those shingles.
The problem with tar paper is that it does not seal around the roofing nails, so any water wicking up that far will get to the roof deck. A properly overlapped double layer of tar paper can be used on roofs as low as 2 in 12, but recommended practice a self adhesive membrane covering the entire roof.
For DIY, Ice and Water shield will work, and is generally available everywhere.
I think the best way to fix your roof is to remove the shingles, remove and discard the tar paper, pull the roof deck and fix the rafter problem. Add / replace rafters as required. Make sure the crown of the rafters is up.
Put the roof deck back down , and apply complete coverage of Ice & Water Shield. Then shingle.
Also, for the header over your door, I would expect a doubled 2x6 as a minimum. A single 2x4 is going to sag and cause problems.