I have a stick framed house that somebody thought would be more useful with a blind valley roofing job. Brand new construction too!
Anyway. The idea is this. In the area of 4 rafters near, but not exactly on, the center of the offshooting roof line, I plan to:
– double the outer rafters
– double the cooresponding 1st floor ceiling joists at the doubled rafters
– add a support or purlin from doubled joists to doubled rafters (where along the joists, or how high should this be, thinking at approximately 48″ from rafter to joist area)
– add an addition rafter from the ridge board down to the double header (will trim to length exactly when cutting existing rafters)
– cut out the two center rafters from a point about 96″ from the floor of the attic area and remove all sheathing between outer two doubled rafters
– install a double header at about 96″ off the ceiling joists of the attic floor below between the doubled rafters
-nail the remaining sections of the cut rafters and the additional third ‘shorty’ rafter to the header
That’s the order of construction and my plan. I have thought about eventually having a 3/4 bath in this area since there is a vent pipe near that could become a wet vent and the hot water heater is right next to this area with hot and cold supplies. This opening would end up having a door that would allow access to the rear attic area.
Okay, shoot it down! I was quoted a grand by the original framers just to double the rafters, add a header and cut out the center. So far I’m looking at around a $100 of lumber and some of my BST.
Replies
Oh I do hope somebody can look this over while I off blowing out a dryer duct under one of my regulars houses..... I really want to get on it tonight when I get in from work.
You're wanting quick structural advice on something pretty serious here.
1. We don't know your local codes
2. We don't know loading requirements in your area.
3. We don't know the size, grade, or species of lumber involved.
4. We don't know the spans involved
5. Etc, etc.
No way you're getting any specific advice on something that vague. Even if you were more secific, I (And most others here) don't like to give out structural advice unless we can see the job
If you are in a spaceship that is traveling at the speed of light, and you turn on the headlights, what happens?
I am actually over building what the original framer was suggesting. We have no snow and wind rate is less than 4mph. Load requirements are low enough they get away with using 2x6 rafters. I guess I am asking more for a 'sounds about right' or a 'you didn't mention a ______ ' more than a complete structural analysis. I am 99.99999% sure that it's a very sound design. I just wasn't sure about the fact there isn't a lower header. All other openings I've ever made in a roof had some type of lower header. Without it, will the purlins provide enough bracing to counter the flex at the bottom? That kind of thing. This is just a conversation, as if we were sitting somewhere and I popped out a napkin and said the same thing. A lot of it is based on Mike Guertin's comments in July 2000, FHB.
Edited 9/24/2002 5:31:00 PM ET by Wilburn Hancock
The fact that they're 2X6 rafters means nothing without other info for a frame of reference. That might be overkill on your house if they only span 8', but might not if they span 16'.
The reason I mention actually seeing the house is that there may be other things to consider that you haven't thought of.
Four MPH isn't a minimum wind load design anywhere in the country that I've ever heard of. The lowest is typically 70 MPH, but they aren't always enforced.
Even if you have no snow, you still have to design for live loads.
Bumpersticker: My child was inmate of the month at the county jail
The rafters are 20' from ridge to top plate outer edge. I don't have the building width, but I'm not going up there tonight. I was wanting to add all the additional framing when I could and worry about the cutting later.
Sorry, the min std is 70. Point was we have low loading stds here.
This whole discussion really doesn't matter I guess. I was going off what the framer who built the house said as to what should be done for this job. I could hire him for $1000 and he'd do it as I described without the doubled joists or any purlins or the third rafter. He was here on the GC's behalf to fix some floor deflection in the back part of the house. We went through the whole attic and I got his specific requirements to do what I wanted to do. He was not going to double the joists or add any type of purlins or knee wall to help counter the lack of a lower header. If I were putting a skylight in it'd not require as much work, but the general concept would be the same. I've done several and only one ever leaked and 5 years later no roofs have sagged. These framers also busted the toenail of one of the attic 'ceiling' joists and just left it reduced by an inch and a half height wise at the end. I thought that looked fishy, but it must have passed code inspection.
My whole reason for asking this is I think the framer was going to go too light on structure. Boards are cheap compared to sag problems and inspection problems.
99.99% sure? Yeah, I had a guy who cut his girder truss apart to make a closet, he was 99.99% sure too.
The "framer was there to fix some deflection problems"? Your using his suggestions? Yeah that does sound fishy.
Your question and your posts, and the fact that your fixing some saggy dryer duct in between structural modifications to your house for which you are seeking counsel on the internet sounds a little fishy too.
Tom
The dryer duct is one of many projects from rebulding furniture, fixing the hot tub, fixing the deck that is coming apart, and so on and so forth for this one family. I _used_ to remodel a lot when I had rental houses to fix up. Whole new kitchens, baths, additions, and of course the repairs. Now just doing more of a 'home repair' type work since I was laid off from my computer job some months ago. I also worked building churches a couple summers. Nothing like framing, sheathing and roofing a building the size of a football field.(maybe it just felt that big) Those summers I got to do everything but drive the Cat D6.
Sorry for the confusion. I have no problems like my client does, their toilets leaked, their windows leaked, the corners are visibly not square so on and so forth. That deflection, a few holes a sloppy roofer didn't chaulk when he pulled the board he stood on to roof the gable and some landscape issues were it. Three things in a brand new home.
You hit what I was thinking. I trust my revised design a whole lot more than his. I know they built it, but they also caused the deflection in the master bedroom. (15'x18' no engineered lumber and obviously not enough footings) I have done enough 'just enough' to meet code mods in the past, never again. The box frame my sat dish pole is bolted to is 2x6 treated, glued and screwed and mounted with 4 bolts to a longer compliment piece nailed to 4 rear wall studs in the eve of the house. It should hold at least 500#. The pay off is my dish mount don't wiggle when the wind blows. Heck, it's attached better than some decks around here. When I sell, just a small piece of eve perf siding needs to be replaced.
I've been looking at this blind valley mod for over a year. I just now decided to get moving on it. It's nothing critical like a roof or a deck that's come off the house. There is no rush. If it takes 2 months of piddling instead of the less than 2 days I'd regularly alot for doing it alone, I don't care. So the storage is stacked in the way a little longer, it's still all in the attic/'bonus' area.
I just felt like the original guys were a little light. I would rather over build and have the added strengh even if it is not needed. (now the waste-not want-nots will be after me)
Okay, here's my last post. I'll let this die. On really important stuff I would usually ask a second opinion. I don't have any friends here in the building trades and I guess after the framers specifications, I _am_ the second opinion. If you look on page 24, FHB 132, July, 2000, you will see something close to what I am talking about. However, that is a mod to a truss roof without a ridge board and mine is truly stick framed. I'm not that ignorant, not all knowing either, but not that inexperienced either. You can be guaranteed that Mike CYA'd that response pretty well. He basically gives the structure to replace the load bearing abilities of the trusses that will be cut in that question. The only part of this mod I have never dealt with is the lack of the lower header. That's it. Period. Every other thing about making this opening I've either done it or seen it done. I've never seen a roughed door opening on a slant, but that's what this is and I question that loss of the lower header on a roof. The fact it is opening into another roofline that is supported elsewhere is not germane and if anything the attached blind valley plates and sheathing will provide the needed structure without the added purlins and knee walls on either side of the opening.
If you are in a spaceship that is traveling at the speed of light, and you turn on the headlights, what happens?
Your battery gets charged!
Mr TDo not try this at home!
I am a trained professional!
Plus, this is not a chat room. Lots of people only check in here once a day. Some, including some of the valuable contributors, not even that often. Expecting a reasoned response after two hours and five minutes is not very realistic.
Not so much expecting, just the 'Hail Mary' of wishes... Besides, I'm home only to wait on my wife to get here and I'm back out again. Have to fix a dryer duct that fell into a crawl space. I try to keep the 1 y/o out of crawl spaces, even if he is a great crawler ;-).
(although if they cast for Mayberry RFD, 2030 he could play Otis the way he walks now)