Rafter ties to span 20 feet

[Catmeds]

What type of wood would offer a continuous span?

We are renovating our garage and have removed a bad roof, dormer and second level.

Next we will remove the joist that supported the second level floor and start building a roof. I was hoping to have a open floor plan.

Thank you.

 

[SGKent]

not to be smart but doesn't the city or county require an engineers stamp on a set of blueprints and a permit for something like that? They usually specify the wood to be used, dimensions, and grade. The engineers here even specify the nail size and number of nails plus spacing. Here the inspector will even measure the distance between random nails, the wood grade, and species.

 

[rsanter]

Not really understanding what you are doing there.
If you are removing a roof and upper floor and want to go back with just a roof, then I would buy engineered trusses made for your application.

If you are going back with a new floor for the upper room and then I would look at the (forget what they call them but they are wood but look like an I beam) and then for loading you set the spacing of them and then build the upper room walls. Then I would do engineered trusses on top of that

Bob

 

[Catmeds]

Thank you for your replies. I'm in the process of getting a permit and they want to know what my plans are for building the roof. The easiest are trusses. The issue I'm having is getting anyone to email or call me back regarding the pricing. We don't have a Menards where I live but I priced trusses on their site, it seems very doable as far as my budget goes. I've emailed three companies in my area and left a message for one (I work two jobs so time is tight for me) but haven't heard back from any of them.

As a back up I'm trying to price how much it would be to build it. We have torn the roof and second level off. The first floor is in good shape but still needs some work by the door that we can easily do.

I'm going to the office today to turn in my plat and a contractor exemption affidavit so I can get the approval. I'm just worried about not having the truss information available to say this is what I'm doing.

 

[Homerr]

Seems like it would make more sense to have a plan before tearing the roof off.

Your basic question about stick building the roof is really has too many factors to give a decent answer. Ideally, you'd have an engineer come to the site and advise you - or, provide an engineer with a very clear set of plans of the existing conditions.

Snow load in your area, span, configuration, where there is existing bearing, ceiling/headroom needed, windows, etc. are some of the factors. It might seem easy as building a roof on a rectangle but codes need to be followed and frequently an old setup can't be reproduced today because of stricter loading/lateral standards or decreased lumber values as we use non-old growth timber.

 

[Falcon67]

Refer to span tables for the type of lumber available. Southern Pine, SPF, Doug Fir, etc, etc. Here as I recall, normal SPF #2 for 20' would be like a 2x10. Example is my 24' span in the shop, we went with 2x12 doug fir to make sure. At that time it was good for 26' total run. In fact I think I ordered 2x12x24 and got 2x12x26s. Note that span tables are updated regularly and ratings change. Rafter sizes same, use span tables because a lot depends on roof loading - snow load, deflection, etc - in sizing roof members.

Here is one link for southern pine = https://www.southernpine.com/span-tables/

#2 southern pine ceiling joist, 10 psf live load, 5 psf dead load - 2x10 @ 16" OC good for 25' 7" (see table 15).

 

[Catmeds]

Thank you for all your comments and assistance. Every bit helped me with the next step. The inspector at the Permit office gave me a lead on the trusses and I've gotten that part taken care. I'm so relieved right now. I'll have them in four weeks and I scheduled a week off from both my jobs to get it done plus I'll have some extra hands to help me.