Strengthen Wall With Single Top Plate

[Needing Advice]

Brief description:

Two story house. Upstairs bedroom has a deck (9*9). Below that is the (bigger) first story deck. I wanted to create a screened in area on my lower deck by framing walls up to the upper deck's rim joists.

However, this would not give me enough room so I decided to expand the footprint by building a small, low-pitched shed roof attached to one of the upper deck's rim joists. It's great, just enough room. But in my haste to finish the project I didn't consider the effect of using a single top plate for the new supporting wall.

The new wall is 2*4, 16" oc. The rafters are 2*4, 5 ft long 24" oc. The total roof area is 50 sqft. 10' * 5'. I sheathed the roof with

5/16 plywood.

I don't think that this is enough load to really cause the top plate to sag but now I've got to thinking about it. One thing that I have to do anyway is to install 2*4 horizontal blocking between each rafter, resting on the top plate. The initial reason for this was to block off mosquitoes etc.

The question is, would this blocking be enough to stiffen up the top plate for such a small roof? Or should I also screw in some 2*4 blocking in between each stud and attach those to the top plate?

Thank you and I apologize if it's long winded. I wanted to be as thorough as possible.

[Dave]

Mosquitoes aren't apt in dark and dry places. What you're describing is bird blocking. Typically, has a hole drilled through it wire mesh screen over the hole, Purpose is ventilation.

Don't walk on that roof, ever.

There are 2 general purposes for the double plate where joists and rafter ride. One is supporting weight strength. Which you seem to address here. The other, you're iginoring. Dave

[Needing Advice]

Yes, I understand that it's called bird blocking but I'm not blocking birds, I'm blocking mosquitoes. :) Perhaps you are picturing a completed house but this is a screened porch wall, there's plenty of light and most definitely warmth.

As I understand it, the double top plate adds rigidity to the top of the wall, helps weight distribution and ties intersecting walls together. The only wall it's connected to is about 3' long, non load- bearing and screwed like crazy to the corner post of the new wall, edge rafter and 6*6 that's supporting the deck above. The other side of the new wall is screwed to the corner post (2*4) of the house.

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So you agree that the "bird blocking" will help distribute the weight of the roof? Should I put blocking underneath the top plate between each stud? I figure the bird blocking should act as a semi- strongback.

[PeterD]

Where is this project located?

[Needing Advice]

In coastal NC. I have used hurricane ties at the "ledger" and will be putting them on the rafter-to-top plate. I haven't finished the wall because I don't know if I want to pull the roof off and do it over. I also need a couple cripple studs above the door but I want to get my bearings first. Also, the rafters are pretty close to the studs.

Here are some pictures. I hope they work.

[Roger_N]

If it were me, I'd add a 2x4 between the studs in the locations where the rafters are not close to in line with the studs. In other words, where the top plate takes the most rafter load. Might not be necessary but the top plate would be reinforced where the load is.

[Needing Advice]

That's what I was thinking about doing but I wasn't sure if it would help. It made sense to me but that doesn't mean much :) Doing that will also give me a nailing surface for the rafter ties. I'll do it all the way around. It should act as a weakened double plate, correct? I say weakened because of all the connections at each stud.

If you were me would you consider pulling the roof off and re-doing it? When I screw up something it bugs me to no end. I think pulling the roof back off would be a waste of time for such a small load.

[Roger_N]

If I understand correctly, roofs are rated at so many pounds per square foot, you don't have near the roof area of a house roof that would rest on a double top plate. If you wanted to strengthen it just to be sure, you could put the doublers between the studs and fasten doublers to studs to support the "between the studs top plate doubler". Basically the same idea as a door or window but without the opening. Notice how the force of the roof load goes to the header and down to the jack studs. You shouldn't need full length jack studs, just something to transfer the load from the "header" between the studs to the studs themselves. I think you could make what you have as strong as or stronger than a double top plate faster and easier than re-doing it.

[Needing Advice]

I had figured that the load was small enough initially but , as usual, I started to over think the issue. However, I now have a different concern that I would like opinions on.

Where the rafter meets the side of the house I did not cut out the cedar siding so there is a small gap caused by the angles of the cedar lap boards. At first I didn't want to go cutting on the siding but now I wonder if flashing it will be a problem? I thought I could just foam and caulk the gap but now I'm worried that water could get trapped and rot the siding. Have you ever used metal flashing on a connection like that?

If I don't cut away the siding the flashing won't be tucked under the siding but instead flush with the face of it and then down over the tar paper. So I might wind up removing part of the roof anyhow. But now that I've got some feedback on the support issue, I won't be redoing all the rafters, just the house connection.

Also, I would use a circular saw on the siding but what about nooks and crannies? Should I get an attachment for my drill to do that part? What's the best way to make smaller cuts in places that a circular saw won't fit or would make too big a cut?

Thanks for the > If I understand correctly, roofs are rated at so many pounds per square

[Dave]

[Needing Advice]

Are you friggin kidding me? What are you getting at? If you don't understand the need to screen/block the mosquitoes out then you're right, end replies for sure... And what are you going on about secondary, primary functions of a double top plate? If you have an opinion then please do share.

[Roger_N]

If you could keep water away from the area you could seal it, if it's going to get wet then it would probably need to get some ventilation to evaporate. I'm not sure what you are planning on for siding your addition but perhaps the trim would keep rain away from the area, and you could seal it up as you planned.

As far as cuts in nooks and crannies, try whatever looks best for the job. A few things that come to mind might be a sawzall, jigsaw, hand saws, Roto-Zip, Dremel tool, router. Milwaukee has a handle that holds sawzall blades "Milwaukee 48-08-0401 Quik-Lok Job Saw" that received good ratings on the Amazon.com website, with all the reciprocating saw blades available, it should be handy saw to have.

[Needing Advice]

Hey Roger-

The siding is going to be aluminum screening with those spline kits from Home Depot/Lowes. When I complete the porch above, the roof for the upper deck is going to be dumping water down to the lower so I think I'm going to cut out the siding and flash it like a ledger connection. Or I could leave it alone and let the gap drain but I think I should probably just flash it. I have seen bad connections like that rot out siding and sheathing.

[Anonymous]

first, as to your initial question, a single top plate for your application should suffice. technically it isn't allowable on load bearing walls for a number of reasons ranging from crushing/bending to edge nailing for your structural sheathing. but this being attached to your home and of such a small area i really wouldn't worry about it that much. next, the "bird" blocking does actually serve a purpose in increasing lateral capacity. you can think of it as either providing a continuous path for the load from sheathing to top plate to the wall sheathing or as a method of keeping the rafters from rotating. so, with that said, installing the blocking and putting nails from your roof sheathing to the blocking at say

4"o.c. would be good. from there some cualking and your mosqito issue is solved. if you plan on putting hurricane straps on the rafters, as you should for NC, i would recommend simpson SSP type connectors at every second or third stud, top and bottom to get the load all the way to the foundation. as for the siding, it would be much easier to just screw into it, making a ledger of the last rafter - cualking that off and putting flashing. either way, attaching that part to your main structure is a good idea - otherwise a good wind may send it flapping a bit against your house..

good luck!

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[Needing Advice]

Thanks man! Lots of good info, I appreciate it.