Looked at a job the other day – couple of ‘businessmen’ are converting a detached garage into a granny flat. Its actually already kinda halfway converted, so I guess they’re really just renovating the conversion. These guys buy property, renovate, and sell. That’s their business. The older one acts like he’s a construction dude “I’d do the framing myself, but I’m leaving town tomorrow”, but admitted to having no actual trade experience other than DIY on his investment projects.
The other guy is young, definitely not a hands-on person whatsoever – apparently the money guy, ‘though. Anyway, they’re converting the small (18’6″ by 26′ 0″) detached garage into a granny flat, before beginning a major renovation on the house.I admit there are some red flags – they asked me to bid the job, but they’ve already begun work (demo). And they have no plans, just a pretty vague little sketch to work off. So I told them I couldn’t bid it, but would work hourly for a figure that I thought would end the conversation, but they said OK to that. So it looks like I’m gonna start the framing Monday – probably just a couple days’ work.Sorry for that intro, not sure why I thought it might matter, but it might. At least it explains whay I feel kinda funny about this one. Anyway, the building is about 18 feet wide, the framing is solid, and the craftsmanship looks good. Looks like 5:12 pitch, hip roof 2×6 rafters 24″ o.c., 2×8 c.j. 24″ o.c., see drawing.They want to put collar ties at about 14″ down from the ridge, remove the joists, and vault the ceiling up to the bottom of the collar ties. The original has 2×4 braces from the ridge to the joists, nailed to a strongback. I’m planning on removing all that, and just putting the collar ties in. They want to run an A/C duct in the 14″ space betw. the ties and the ridge.Any input would be appreciated. I’m wondering is this structurally sound? Its just a tiny little building, but I like to do things right. No blueprint, no engineer (their choice), but I still want to follow protocol. Is the placement of the collar ties critical? Do I need to be concerned about venting where the sheetrock is nailed to the bottom of the rafters, or does air flow through fiberglass insulation well-enough?View Image
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Red flags and flashing red lights.
Yes you need to be concerned aboiut air flow ... it does not flow through fiberglass insulation at all. Placement of the collar ties is very critical. My guess is that the garage was built to mionimum standards anyway ... hey, it's a garage for a car ... just nail it up! I would insist on a visit by an architect or engineer before the first cut is made in the rafters, or else I would walk away. If they won't go for the engineer, I would not even bother with a signed waiver ... just start walking.
I'm sorry, I thought you wanted it done the right way.
Nope, not structurally sound. Might not fall down, but will definately sag and crack like crazy. How do you feel about callbacks? It needs some sort of structural ridge, or rafter ties placed closer to the top plate. Like Ed said, insist on professional input--that little voice in your head is right.
Mike
Thanks Mike and Ed - appreciate the input. I'm going through the archives researching "collar ties" and "rafter ties", and I'm starting to see the problem. Apparently collar ties, being so high up, can't counteract wall-spread like a c.j. or rafter tie would.
You still need professional input, but one option might be to leave every third ceiling joist to help keep the walls from spreading. Assuming the rafter/joists are at 16", that would give almost 4 ft of clear space between joists and could enhance the appearance.
I'm sorry, I thought you wanted it done the right way.
"Is the placement of the collar ties critical?" Definitely yes. Collar ties should be no more than 1/4 way up the rafter. You'll have a flat roof before long! Leave it - if it's only a 2-day job do another one that you'll feel good about and will do you credit...
ciao for niao
To those who know - this may be obvious. To those who don't - I hope I've helped.