Does adding gable dormers obliges changes to the structure of the 20x30 1.5?

[sharbin]

I am planning on adding 2 gable dormers on each side of the 20x30 1.5. Does this change anything in the structure? As an example, do I need to use ridge beam instead of ridge board? Is there a limitation on the number of dormers that I can put? sizes?

Thanks

Sharbin

[John Raabe]

Assuming you will do a 3 or 4 bay gable dormer (6' to 8' wide), all you really do is double the main rafters on both sides of the opening (this is what the dormer sidewalls will rest on) and header off this opening at the top and bottom.

There should be a diagram of this and a shed dormer in the booklet that came with your plans.

[sharbin]

Thanks John for the info.
I don't think that dormer plan came with the booklet. There is the cathedral ceiling one but not the dormer (gable or otherwise). That would be really handy if a dormer plan is available.

Sharbin

[sharbin]

I saw in one post that you referenced to 11-20a sheet for the dormer. Either I lost this page or did not come with the booklet. In either case, could you send that page to me?

Thanks

[John Raabe]

I see in my records that your plans were ordered over a year and a half ago. That was before that sheet was added to the 1-1/2 story plans in an update.

If you have a PlanHelp membership that update sheet is available as a download from this page from the download library:
http://www.planhelp.com/public/programs/downloadsearch.cfm?searchtype=simple&searchmode=cat&keywords=recent&sortby=name&cat=Plan%20Details

Let me know if that helps.

[sharbin]

Unfortunately, I do not have a membership. I tried to link to it but was not allowed. Can you email it to me?or do I have to purchase a subscription?

[John Raabe]

Check your email. I find I am able to send the PDF file to you from here.

[sharbin]

Thanks.

[sharbin]

In the plan a collar tie is shown to tie the opposite double rafters together. This is fine on the loft part. But what about the cathedral ceiling part; I am planning of having another 2 gable dormers on the open ceiling part (see photo). Can I just build the dormers without the collar tie as I have ceiling joists tieing the 2 walls. Would that be sufficient?

[John Raabe]

In the cathedral section of the plan you can tie the rafters together with the built-up beams shown in the booklet. You do not need collar ties for these as the beams serve as ties. I would suggest a tie for each doubled rafter that will serve as bearing for a dormer wall. Otherwise they can be 48" o/c (every other rafter). Check this locally with your inspector - especially if the dormer is wide or snow load is heavy.