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Old 09-25-2017, 11:13 AM  
SidecarBob
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Default Questions about building snow roof over deck

Background:
I live in South Central Ontario and I have a 6' x 20' deck at the back of the 23 year old brick veneer house that was built by the contractor who built the house. It is approx. 42" above grade and supported by a ledger/joist attached to the wall and four 4x4 posts right at the outer edge. The posts are set on bricks, about 4-5" below grade and end at the railings, approx. 43" above the floor. It is framed with 2x6s (all end nailed - no joist hangers) and the floor is 2x4s.

We have always shovelled the deck in winter so that the laundry room door and patio door could be used as emergency exits (fortunately never needed so far). A few years ago we had the roof done with steel shingles and now the snow slides off regularly, filling the deck. One morning last April I woke to 6" of snow on the deck and an hour later heard the "avalanche and the snow was almost up to the deck's railing (that time I only cleared from the laundry door to the stairs - it all melted within a few days anyway).

The project:
I have been talking about putting a roof over the deck to carry the snow past it when it slides off for years and always forgot when I wasn't shovelling it off but we had a heat pump installed last year and I want to get to the project before it is damaged by the snow sliding onto it. The heat pump is on legs on the ground (on patio stones), right near the end of the deck so I figure if I build the roof 4' longer than the deck it will protect the heat pump too.

Question #1:
There is 89" between the deck floor and the soffit.
Assuming the framing doesn't overhang the edge of the deck (the steel can go an inch or so past), 2x6 framing and an inch + for corrugations in the metal, if there is 72" from the floor to the top of the roof at the outer edge the bottom of the edge of the edge joist/facer will be about 65" above the floor and any lower will render the deck useless.
That means that the pitch would be approx. 1 in 4.25 (2.83 in 12). Is that enough pitch for straight steel panels to shed snow?

Question #2:
I really don't want to dismantle the deck any more than I have to and I don't want to pour footings. Can I cut the bottom end off of each of the existing posts and put deck blocks under them?

Question #3:
If I do that would I be better to extend the posts to support the outer edge of the roof by
A) Extending them with lap joints bolted through (not my favourite idea)
B) Sandwiching the original posts between 2x4s (or 2x6s?) (not the best looking solution)
C) Cutting the posts off at floor level and building a 2x4 (2x6?) frame wall to support the roof. (I am leaning to this idea.)

Question #4:
If I build a framed wall I would still need an additional post for the part of the roof that would be over the heat pump. Would I need to build the framed wall all the way to that post or can it end at the end of the deck?

Question #5
The existing outer edge joist is currently a single 2x6. I expect that if I build a framed wall on top of it I would need to add material for it to bear the load. If I did that I would want the added piece to extend to the post supporting the end of the roof above the heat pump to stabilize it.
Can I just nail another 2x6 (2x4?) to the existing one for that?

That's all for now. I'm sure I will find other questions as I figure out what I need to order for this...


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Old 09-25-2017, 11:35 AM  
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You get away with the deck sitting on blocks because the deck can flex when the ground freezes and that may pull nails from the ledger.
You do not get so lucky with the roof. You would want footers and piers to support the roof.

For starters while you think it over I would build a dog house roof over the heat pump to protect that and keep the snow away from it.
You could just add a skirt roof to move a snow a little further from the door.
Or snow stopper thingies they put across the steel roof to slow the snow slide.


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Old 09-25-2017, 11:50 AM  
bud16415
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The first problem I see is that your deck is connected to the house on one side with a ledger and the other side and center posts are free floating. We live just across the lake from you and have similar winters and maybe even more snow. My deck is built free floating but not connected to the house so with freeze thaws it can move independent of the house that has deep footings and does not move. You will be seeing maybe an inch of movement on one side of your deck and zero on the other if I’m reading this right and that movement will work on those nail connections until something fails.

If the deck is 23 years old that is a good sign that the structure is somehow working configured like this. Replacing the bricks with the precast footings won’t really change much and should be no worse than the bricks I think.

I just had a steel roof put on this summer and I have a similar situation where the house roof will shed snow to the deck roof. I will be watching this closely as I didn’t have them put the snow retainers on but I have a box of them if needed. Time will tell.

What pitch is on your main roof and what pitch will be on the new deck roof?

You might want to think about the snow retention clips as well.
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Old 09-25-2017, 12:51 PM  
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Even though the house is fairly new and built to modern standards I like the idea of the snow coming off the roof on its own. We haven't been having as much snow in recent years but there is always the chance of a heavy year. Which adds up to I would rather not add the stoppers if I don't have to. BTW: We had the eaves troughs done at the same time as the roof and the sliding snow doesn't seem to have loosened them at all. That was 9 years ago when the "25 year" asphalt shingles failed.

FWIW, I was under the deck re-caulking a couple of windows last week and the framing seems to be tightly together so the nails don't seem to have pulled out. So far. I wonder if that has anything to do with the bricks that the posts sit on being a few inches below grade?

I am thinking about the precast footings for 2 reasons: 1) to support the extra weight (they would have about 2-3 times the area) and 2) The outer edge has a bit of a sag. Most people don't notice the sag but I inherited my Dad's eye for straight & level (he was a carpenter/cabinet maker for most of his career) and it bothers me. This would be a good way to get it back up to level.

The house roof has a 7 in 14.5 pitch (1 in 2.1) and if I build the deck roof as described above it would have 1 in 4.25 or about half the pitch of the house roof. That is my big concern because if it isn't enough there is no point doing it unless I rip out the whole deck and rebuild lower.

I think Erie gets more snow than we do. We are in what some people refer to as Ontario's "banana belt", getting about half the snow that people living half an hour's drive north or south of here get and a lot less than they get near Lake Ontario. I think it is because even the biggest lake near here (Lake Simcoe) freezes over completely most years so there is nowhere west of us for the wind to pick up moisture to drop on us.
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Old 09-25-2017, 01:07 PM  
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Perhaps there are footing under the deck and some one raised out of the dirt with bricks. They will be 3 1/2 to 4 ft in your area

Pitch is understood better if it si stated as rise over 12" as in 6/12 or 9/12.
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Old 09-25-2017, 01:58 PM  
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Sorry. The house roof is 5.75/12 and without lowering the deck its roof would be 2.83/12.

I stopped digging when I found the bricks. I could dig a bit deeper and see but I doubt that there is any concrete under there. The house has been in our family since built (we inherited it from my parents); I know I haven't ever dug around where the posts go into the ground or raised the level of the soil in the 17 years we have lived here and I'm pretty sure my Dad didn't either.

I could dig down a bit more to see what's under the bricks but its 30c out there with the sun hammering down on the back of the house so it will have to wait until it starts to cool off.
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Old 09-25-2017, 02:07 PM  
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Quote:
Originally Posted by SidecarBob View Post
Sorry. The house roof is 5.75/12 and without lowering the deck its roof would be 2.83/12.

I stopped digging when I found the bricks. I could dig a bit deeper and see but I doubt that there is any concrete under there. The house has been in our family since built (we inherited it from my parents); I know I haven't ever dug around where the posts go into the ground or raised the level of the soil in the 17 years we have lived here and I'm pretty sure my Dad didn't either.

I could dig down a bit more to see what's under the bricks but its 30c out there with the sun hammering down on the back of the house so it will have to wait until it starts to cool off.
Get a 4 ft piece of rebar and pound it in on angle and see if it will go under the brick or run into something solid.
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Old 09-25-2017, 04:35 PM  
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And under the brick is.... Drumroll please... Gravel
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Old 09-25-2017, 04:43 PM  
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Post a picture so we can see what your seeing please.
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Old 09-25-2017, 04:43 PM  
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Quote:
Originally Posted by SidecarBob View Post
And under the brick is.... Drumroll please... Gravel
My story stays the same. you would need footers


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