Roofed pergola plan feedback

[rgv]

Plan to build a roofed pergola on the balcony of a 2-store house. The plan is attached, removed rails from the schema for visibility.
Can't drill the structure or walls.
For the ground and load-bearing parts plan to use 4by4 in pressure-treated posts.
To connect 4by4s plan to use mortise and tenon joints, Titebond III Ultimate Wood Glue and wood screws.
For the longest parts that connect load-bearing posts on the top plan to glue together two 4by2s to make it stronger than 4by4. The distance between load-bearing posts is 4m and 2m.
The roof will be covered by polycarbonate.
Trying to make it sturdy in case the snow+rain accumulation on the roof since the slope is just 1:12 Pitch=5°.

Any advice or comment is appreciated.

 

[slownsteady]

Can't drill the structure or walls.

I'm not sure I understand this. Will everything be supported from underneath? Nothing fastened to the structure? So essentially a freestanding deck, two stories up....

 

[rgv]

yeah.. attached the picture of the current state

 

[Snoonyb]

If the floor joist of the deck you are proposing to install this pergola on, are not already cantilevered, and are simply attached to the outside of the dwelling, the posts and beam are very simply a fulcrum, so get this certified by a structural engineer, of leave the roof uncovered so there isn't the possibility of roof loading from snow.

What are your handrail plans?

 

[rgv]

If the floor joist of the deck you are proposing to install this pergola on, are not already cantilevered, and are simply attached to the outside of the dwelling, the posts and beam are very simply a fulcrum, so get this certified by a structural engineer, of leave the roof uncovered so there isn't the possibility of roof loading from snow.

What are your handrail plans?

This is how the balcony to building attachment looks like. As I understand it is not cantilevered

 

[Snoonyb]

Thanks, I would definitely have an engineer review the plans.

 

[rgv]

I was hoping it should be built as per local requirements: 100 lbs per square foot
the balcony area is 100sq ft. => it should hold 10,000lbs = 4500kg.
The pergola weight + snow + people is way less than that

 

[Snoonyb]

I see your deck platform as a 40lb. live load with the post and beam as a center fulcrum, which you stand the chance of loading at the far point of that fulcrum, because of roof loading, and counting upon the fasteners as resisting.

Even though the fasteners appear to be into solid wood, any honest engineer will tell you that the first twelve inches of milled lumber is discounted because of inherent splitting from drying.

 

[rgv]

What if I put two 4by4 posts to support the balcony floor where it attaches to the building, one for each corner?

To avoid extra load from snow plan to use cable for snow melting.

 

[Snoonyb]

Were it I, and it isn't, I'd move the existing post and beam out to near the edge of the floor, and also undermining the slab, beneath the posts, with about 8" of concrete, where the balance of the load will be carried, I wouldn't worry about the portion of the load carried by the hangers, other than to solid block between the joists beneath this 2 posts.

 

[bud16415]

If it were mine and again as post above it isn’t. I have a Sunsetter Awning that rolls up all winter. We have one and it gives great shade to our hot tub deck and we leave it up most of the summer months only closing it if there are expected high winds. Ours has a manual crank operator and it takes a couple minutes to roll it out.



Over our actual hot tub we have a solid pergola that I built and it really did nothing except look nice and I added a tin roof to it the first winter it was up. It has had several foot of snow on it and rests on the deck. My deck has substantially greater structure to it than what you show and I felt ok with supporting it on the four corners.



For sure play it safe and have a pro run the numbers before you build would be my advice.

 

[Steve123]

You may want to review THIS.

 

[rgv]

Sunsetter Awning

Requires to drill the house wall. Can't do.

move the existing post and beam out to near the edge of the floor

Doesn't this add more load to the joists?

I see your deck platform as a 40lb

The balcony is 100sq ft => 100*40 = 4000lb or 1800kg. I think that adding ~200kg pergola shouldn't overload it, especially since the pergola structure puts the load on the edge joist stuck together. At the same time agree that it could be close to the max load, found this doc
https://www2.bchousing.org/sites/de...aintenance-matters-22-balcony-overloading.pdf.

I attached a video for more context on the balcony supporting structure.

Will try to find a constructor that builds such things to consult.
View attachment video_2024-03-30_09-53-22.mp4

 

[BvilleBound]

First, thank you for the video which helps to explain the dimensions and current construction details:

1. There is apparently no need to relocate the posts. Roughly 25% of a joist can extend beyond the supporting beam. They appear to be fine, and you can measure to confirm.
2. The key question is the ‘ledger board’ attached to the house. It MUST be securely attached to the house with bolts or lag screws driven into the framing of the house. I ask because many decks are not, and this is a key point of failure. I even saw a deck ledger nailed to wood shingles! It was amazing that it had not collapsed and seriously injured or killed someone. Read the Simpson guide to deck fasteners, which explains the requirements: https://www.strongtie.com/resources/literature/deck-connection-fastening-guide
3. RE your pergola addition, if the ledger board is securely attached to the house, the added weight should not be a problem. You should use Simpson brackets to fasten the pergola post bases to the framing of the deck - don’t simply use nail or screws, and do NOT attach the pergola to the thin decking. Also connect the pergola beams to the pergola posts with Simpson brackets. If you cannot fasten the pergola frame to the house (which would be wise), Simpson brackets will be essential to strengthen the pergola structure. You should also add corner and cross bracing, particularly if you have any wind in your area.

Read the excellent Simpson deck design guide for all of the details. I have no connection to Simpson, by the way, except as a happy customer.

I hope this is helpful.

 

[Snoonyb]

Requires to drill the house wall. Can't do.

Doesn't this add more load to the joists?

The balcony is 100sq ft => 100*40 = 4000lb or 1800kg. I think that adding ~200kg pergola shouldn't overload it, especially since the pergola structure puts the load on the edge joist stuck together. At the same time agree that it could be close to the max load, found this doc
https://www2.bchousing.org/sites/de...aintenance-matters-22-balcony-overloading.pdf.

I attached a video for more context on the balcony supporting structure.

Will try to find a constructor that builds such things to consult.
View attachment 32472

Interesting; So, a 40lb live load, changes at the fulcrum too....................?

Moving the support accomplishes two things, it eliminates the fulcrum, and places the support for the potential gain in loading, under that additional loading.

Here is a link that may serve you; https://www.thebluebook.com/

Just fill in the blanks, "civil engineer, structural engineer, etc".

As an afterthought, I ounce encountered a land coverage issue, similar to yours. The required rear yard open space could be intruded, marginally, by patio slabs but not roofed structures supported by a foundation, which oddly may have been addressed by the placement go the post and beam support for the deck.

 

[rgv]

First, thank you for the video which helps to explain the dimensions and current construction details:

1. There is apparently no need to relocate the posts. Roughly 25% of a joist can extend beyond the supporting beam. They appear to be fine, and you can measure to confirm.
2. The key question is the ‘ledger board’ attached to the house. It MUST be securely attached to the house with bolts or lag screws driven into the framing of the house. I ask because many decks are not, and this is a key point of failure. I even saw a deck ledger nailed to wood shingles! It was amazing that it had not collapsed and seriously injured or killed someone. Read the Simpson guide to deck fasteners, which explains the requirements: https://www.strongtie.com/resources/literature/deck-connection-fastening-guide
3. RE your pergola addition, if the ledger board is securely attached to the house, the added weight should not be a problem. You should use Simpson brackets to fasten the pergola post bases to the framing of the deck - don’t simply use nail or screws, and do NOT attach the pergola to the thin decking. Also connect the pergola beams to the pergola posts with Simpson brackets. If you cannot fasten the pergola frame to the house (which would be wise), Simpson brackets will be essential to strengthen the pergola structure. You should also add corner and cross bracing, particularly if you have any wind in your area.

Read the excellent Simpson deck design guide for all of the details. I have no connection to Simpson, by the way, except as a happy customer.

I hope this is helpful.

Thanks for the detailed response!
I'm not sure if the ledger board is attached securely. Adding a video and pictures. Any guesses?

 

[rgv]

Interesting; So, a 40lb live load, changes at the fulcrum too....................?

Moving the support accomplishes two things, it eliminates the fulcrum, and places the support for the potential gain in loading, under that additional loading.

Here is a link that may serve you; https://www.thebluebook.com/

Just fill in the blanks, "civil engineer, structural engineer, etc".

As an afterthought, I ounce encountered a land coverage issue, similar to yours. The required rear yard open space could be intruded, marginally, by patio slabs but not roofed structures supported by a foundation, which oddly may have been addressed by the placement go the post and beam support for the deck.

any chance you know the Canadian analogue?

 

[Snoonyb]

any chance you know the Canadian analogue?

What a waste of time.

It isn't listed for Canada, and had you listed your location, as a courtesy, I, as a courtesy, wouldn't have suggested it.

There are several contributors here-in, located in canada, so maybe they'll chime in.

 

[BvilleBound]

Dear RGV: Thanks for the additional photos and video.

First, the tripled-up joists on the sides of the deck appear to rest on a post or maybe a double/tripled ‘king’ stud at the corner of the house. This would obviously provide strong support for that side of the deck. The framing is covered by the dark gray trim board, however. Can you see behind it or pry one of the boards back to check?

Second, I did not see the large heads of Simpson or other lag bolts used to fasten the ledger board to the house. They appear to have used standard nails or screws, driven deep into the wood. So this is an essential safety upgrade. See this data sheet and note the required installation pattern on page 2. You will need to measure your ledger board to buy the correct number of lag bolts: https://deckbuilderoutlet.com/simpsonledger.pdf

Simpson also makes decorative black brackets for decks that you could use to connect the framing of your new pergola. See:
https://www.strongtie.com/decorativehardware_woodconnectors/category

I hope this is helpful.

 

[rgv]

What a waste of time.

It isn't listed for Canada, and had you listed your location, as a courtesy, I, as a courtesy, wouldn't have suggested it.

There are several contributors here-in, located in canada, so maybe they'll chime in.

why a waste of time? Everything you posted works differently in Canada? or is the link to the US website is waste of time?