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Hey guys need some advice on a possible job a customer wants me to do.
It's a loft in an old house and it's being converted into a office/bedroom.

Take a look at the pics below and see if you can advise me better on this. I have my ideas but wanna check with you lot who know more about this than i do. It's my first loft conversion so it's all new to me.


1.See the small knee walls in the picture circled in yellow. Are these framed like this specifically to support the dorma roof framing. Can they be taken down to just 2-3 2x4's. As they are resting mid span on a 2x4 on top of 2 2x4's.
So basically remove the framing in red and replace with framing in green as i want to build the dwarf walls around the room to seal up the eaves.





2.See the areas circled in yellow. The valley rafters and hip rafters are larger in size than the rafters so whats the best way to frame out whats there to hang drywall. Do i just shim out all the rafters the correct distance or run some furring strips perpendicular to the rafters to bring them out. Or is there another way. Also whilst on this subject what would be the min amount of insulation i would need in this loft. currently i would be lucky to get R13 in there but spray foam would get me about R26 or more when shimmed out.




3.This one seems simple but i have some worries. I need to tie in to rafters either side of the roof. Span will be 11ft so im guessing 2x4's will be fine for this but im thinking of using 2x6's for more structual strength between the rafters as the roof has some serious deflection when wind hits it. Just pushing with my hand can move that roof in and out about an inch. Will the 2x6's being tied in like the picture really stiffen that up at all and is there anything i need to know when i tie them in like this?




Thanks guys
 

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hack of all trades
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I have a similar project adding a small "lofted library" in a turn of the century house. I'm not starting it for a while, but I'm interested to see what advice you get. I'm not working with nearly as much headroom so still haven't come up with definite insulation strategy.

If there's noticeable deflection from the wind you should definitely stiffen it up by adding 2x6 to make 12" OC (The old rafters are 5.75" or true 6" id assume, so they wont be on the same plane without more shimming). It would be nice to fasten the sheathing to your new rafters, but until re-roof, that ain't happening.

It will be my first time working on something like this also, so I don't have anything too valuable to add
 

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1) I would not have any issues with removing the framing in red and re frame in the green.
2) String from hip to hip and pad down the jack and common rafters. You have a deeper rafter bay for more insulation and straight ceiling. You might seriously consider sistering the existing rafters or add rafters in between the existion ones.
3) If you are going to hang a ceiling from the new collar ties, 2x8 or 2x10 depending on collar tie layout. If the collar ties are going to be exposed and the ends nailed 2x6 would work. If you are going to through bolt the ends of the collar ties 2x8 might be better. The 2x8 would provide more of a surface area for a through bolt pattern. Foam insulation in the ceiling would help stiffen the roof.

Just my 2 cents.

Looks like a fun project!
 

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You need to start with looking at the floor joists. There's a good chance they aren't sized for a decent floor load.

You'll need to do some calcs on how much roof load winds up being transferred to the floor joist at the dormer corners to figure out if you need to double up, triple up the floor joists where the dormer corners are.

You already know the roof framing isn't very stiff. The cross ties will help out - check the span tables to see if it's enough. If this is a hipped roof, run them both directions.

These can get pretty costly on call backs for drywall cracking. Movement that's structurally OK for a roof is not necessarily OK for drywall. Don't plan on attaching any of the drywall to the roof structure and float all the corners if possible.
 

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We did a similar type of project just on a newer house. The largest pain in the but was doubling up floor joists because they didn't meet code requirement for the load. Took 4 of us two days because they had flooring down up there we had to pull up, but the amount of wires and such that was in the way was crazy.

As far as the hip rafters to regular rafter issue, we ripped 2x and furred out the regular rafters. If they're very uneven you may need to just nail to the side instead of ripping and nailing to the bottom of the current rafters.

We used 2x6's for the collar ties and used a laser to level them which worked quiet well. I think we were spanning roughly that far but our roof structure wasn't moving so I'd probably consider 2x8's but I'll leave that to guys with more experience.
 

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Couple more things.


When you insulate the roof, you will more than likely have to add baffles in the rafter bays, and, if there is no existing ridge vents and soffit vents, you'll have to install those. The baffles are to keep an air chase open between the underside of the roof, and the insulation. If you decide to spray-foam, I'm not sure what you'd do, I'd have to look up how that is done in a cathedral ceiling, as I don't work with spray foam.

Also, check the foundation. It might not be up to code for a 3rd story. Or second. I lost a project just like that one because of the foundation issue (slab-on-grade).








Delta
 

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Couple more things.


When you insulate the roof, you will more than likely have to add baffles in the rafter bays, and, if there is no existing ridge vents and soffit vents, you'll have to install those. The baffles are to keep an air chase open between the underside of the roof, and the insulation. If you decide to spray-foam, I'd have to look up how that is done in a cathedral ceiling, as I don't work with spray foam.

Also, check the foundation. It might not be up to code for a 3rd story. Or second. I lost a project just like that one because of the foundation issue (slab-on-grade).








Delta
Good point on the baffles. We did those as well.
 

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Yes, check the floor (ceiling?) joists to be sure they make code for the floor. If you sister up the rafters with 2X6's it will flush you up with the hips and valleys and add some deflection resistance to the existing roof and straighten it up at the same time. I think 2x6's for the collar ties should work fine.

Definitely baffle every bay of that roof. Those cedar shingles need to breathe.

Good luck.
 

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We just did A similar project. we firred out the rafters with 2x4s on edge using a 6'' pole barn nailer. For the collar ties we used 2x4s and a single king post. We set up the line laser on the bottom of ceiling height on one end and worked towards it.
 

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smeagol said:
We just did A similar project. we firred out the rafters with 2x4s on edge using a 6'' pole barn nailer. For the collar ties we used 2x4s and a single king post. We set up the line laser on the bottom of ceiling height on one end and worked towards it.
6" pole barn nailer sounds terrifying
 
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