Question for Contractors - specifically roofing

[Tidybuoy]

I need a new roof - bad.

My house currently has wood shakes but will have to be replaced with an asphalt shingle. I'm looking for a nice dimentional shake that is better than the old style, plain, boring, etc.

That said, my existing roof has issues. When the house was built in 1949, they spanned the roof too big with not enough support under the roof rafters. This has caused the roof to have minor sagging and some wavyness.

I've talked to a few contractor friends and I'm trying to find out what I should do to make the roof surface perfectly flat and what's the best way - I get different answers every time (but, in fairness, nobody has actually ciimbed into my attic).

I've explained that I currently have solid sheathing. That is, 1x6 boards that have no spacing between them. Not spaced sheathing and not plywood or chipboard. The roof has a couple of minor leaks so there is going to be some boards that will have to be replaced due to rot (I'm sure).

What I think I need to do is add supports (similar to trusses) to hole up the 2x4 rafters. The rafters are currently 24" centers and have collar ties. It also looks like someone at some point tried to brace up the rafters but only did part of the house and I don;t think it is done right.

MY Questions:
1) do I replace the entire roof with plywood and shore up the rafters once the sheathing is reomoved? Seems the most exxpensive.

2) do I remove some of the sheathing (for access) and shore up the rafters.

3) Do I remove all of the collar ties before doing anything and then replace the collar ties after the roof is flat.

4) I'm on a limited budget and the roof is 40 squares, so removing the whole roof and starting over is not an option. Plus, it's made it 60 years so it couldn't be that bad.

5) There is a load bearing wall running the entire center of the house (basically equal to the roof ridge), however, it shifts 4' over in the center (at livingroom) and then back to the center. I'm guessing that walls that seperate individual rooms are also load bearing - I'm saying this because I think any supports need to be above a load bearing wall. The ceiling trusses are all 2x6 and are 16" centers.

6) The roof is 70' long, not counting the garage which is detached but is still part of the overall roof - the breeze way would basically have two load bearing walls.

My ultimate goal is to have a new asphalt shingle roof that is not wavy as I think the shake roof hides a lot of the imperfections.


I put some attic photos below that give a general idea. The roof is long and flat with no gables and is 4&12 slope.

Thanks for any and all advice........Vern

[looneybin]

you need to add some purlins and kickers down to the load bearing walls to provide additional bracing for the roof.

The sheathing is OK, it doesn't need to be replaced unless it rotted

let me know if you need help - but i'm not going up in the attic if its 100 deg

[A930Rocket]

If the rafters are 2x4's, then they are really over the limit by todays standards, especially if they are 24" OC. The 1x4 decking and roofing are weighing it down. Asphalt shigles might make it worse due to weight, without support.

Adding plywood, osb, etc. to the roof won't do much without the rafters being supported or replaced.

You might be able to a few things, but I'll leave it to an enigineer:

1- Replace the rafters and/or 1x4's decking and brace to proper load points below.
2- Scab on 2x6's or 2x8 to the 2x4's from the ridge to the outside plates. You'll need to replace the ridge with a 2x8 or 2x10, depending on which rafter you go with, or maybe scab on a 2x to the bottom of the existing ridge. Current code requies it do be as deep as the rafter.
3- Add more bracing (a lot more) and collar ties.

One problem without replacing the whole roof, is getting the roof flat by bracing. It will take a lot of work to get it flat.

I'm sure there are more ideas out there and others will chime in.

[scottmandue]

Just a FYI that appears to be asbestos insulation on those ducts.

[looneybin]

Originally Posted by scottmandue

Just a FYI that appears to be asbestos insulation on those ducts.

yep - i revise my offer to go up there

[Zeke]

The framing looks light but as they did in '49. Not sure why you're getting sag, you've got purlins and I see a kick brace. There sure could be more bracing and vertical supports.

However, the rafters and purlins have taken a set. They won't move up nicely as you would like. I'd add necessary bracing with a little upwards pressure during the installation. The roof won't sag any more and at best, may correct itself a bit with a couple seasons of constant temp and humidity changes.

New comp roofs need plywood sheathing. To not add weight you would remove the board sheathing. But, if you add the bracing, no need to do that. You could table saw some sleepers that level the roof from rafter end to the ridge and nail the new ply sheathing over those. Probably take out most of the sag and wave.

If you do take off the boards, then it would be much easier to straighten out the roof with some sister rafters. You could do that with 2 x 4's. That would be the cleanest way.

[TimT]

Funny I see gaps between every board...

My house was built in 1929? the roof construction looks similar,

Also I found receipts that a new roof was put on my house in 1974..... I re-roofed in 2009.. I had a roof leak so I suspected I would be replacing a lot of the substrate..

I was home when the existing asphalt shingles were stripped and took the opportunity to check out the wood... the area where I thought the leak was, was fine... In all the wood looked fine... I did have to replace some T&G along the gutter edge...

I think when the existing shingle are stripped you will find the wood planks are in pretty good shape...you will probably have to replace some... but most is still ok to place a new roof on...

Shoot a picture of the sagging.... it may be that some of the supports you see in the pics you posted rest on bearing walls... and other areas of the roof system are less supported..

[Zeke]

The reason I said he needed plywood is because of the shear value it provides. All of CA is considered earthquake country and beefing up shear is mandatory when reroofing.

Plus it adds to the way the comp shingles lay down. If you've seen a comp roof directly over wood shingles (or even over another architectural grade comp roof) you've seen a nasty looking roof.

[Tidybuoy]

Originally Posted by looneybin

you need to add some purlins and kickers down to the load bearing walls to provide additional bracing for the roof.

Ok, I understand the "Purlins" but I can't find anything on the internet that defines "kickers" other than tennis shoes & Karate.

It looks like my roof has purlins that span about 70' and are obviously sagging. They have supports about every 20 feet.

My guess (uneducated of course) would be to locate the proper place for the purlins, and remove the one or two 1x4's so that I can access from outside. This would be aftere stripping off all of the shingles.

Next, I would run a level string on the outside of the roof and put in the purlin braces every 24 or 48" (which ever cooresponds to a ceiling joist).

I'm on a limited budget so I plan on doing some of the work myself and using some laborers to help out. I have about $15k to spend but I'm hoping for a 25K roof and contributing a lot of personal labor. I may need to take two weeks off from work to accomplish this.

My last Question:

After stripping the roof of all shingles, would I put any type of overlayment (like 1/4" 4x8's tp smoothe the whole surface out? Or will the roofing underlayment solve that issue?

Thanks in advance for all the tips. This at least, leads me to endless internet searches and I'm slowing getting the point. This will be a next summer project, so I have some time to do my research.

Thanks All........Vern

[Tidybuoy]

It's very difficult to see the roof sag:




The ridge line is fairly level (hawever a level line my reveal otherwise). The bulk of the saging is where the purlins have no support.

Basically, if you make an "A" shape with your hands, and then curve the sides in a bit.

I'm pretty sure I know what I'm in for....now to get motivaged.

[Zeke]

Kickers are the angled bracing down to a bearing point.

[A930Rocket]

Here are some thoughts based on how we stick frame new roofs here.

Since it's sagging already, you have to not only re-inforce it, but level it out using some jacks most likely. Maybe even raise it past what you need, so it when you re-inforce it, it will settle down where you need it.

[Zeke]

Kickers, also known as struts or knee braces.

Doesn't get any better than what 930 posted.

[john70t]

For that length of span, a 1" x anything ridge beam looks undersized even for the layman. My short garage has a 1x6 and it is sagging.

There are look-up charts on the internet for span calculations, and the local inspector(anonymously) may have some info on this.

This is one idea. It has an accessable crawl-way for servicing, with ample lighting.
The collar ties are lowered and reinforcement was added:

[Tidybuoy]

WOW! Great info from all - thank you.

Looks like I have my work cut out but since I am in the "planning" phase, I have time to think this through and figure out my true expense.

Thanks again.......Vern

[Flieger]

Why not just hire a roof girl?

[Tidybuoy]

The best part of being poor is that I have plenty of time to plan things out.

[Drisump]

You've got some good advice here, on light rafters with low pitches, and with significant spans, you really need to make each pair a truss or support with purlins. Unfortunately, it will be very time consuming and I think with the 24" centers you may still have to add ply to achieve the flat look. Cheers