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Old 02-13-2018, 03:09 PM   #1
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Preparing Attic Space for Future Upgrade


New here, but not new to forum life. Been an active member in a Ford Truck Enthusiast Diesel forum for 11 years, so I am clear on good forum etiquette.

Name is Pete, and I've been a lifelong DIYer ever since I was old enough to hold a saw and hammer in my hand... roughly 50 years now. I do virtually ALL of it... electrical, structural framing, interior finishing, hardwood/tile flooring, appliance repairs, plumbing, sheetrock, minor concrete work, minor roof repair, doors, windows, decks, cabinets, furniture making/repair/refinishing... but I do NOT do masonry! Have owned and remodeled several homes built anywhere from the early 1920's up to my current home which was built about 32 years ago.

Current project is to enhance the unused second floor attic space over our trey-ceiled family room (first floor). There is additional attic space over the second floor bedrooms and baths, but we don't need access to that and it's being left as is.

The interior attic space structure can be described as follows:
- 2x8 joists spanning 15', 24" centers
- roof rafters are 2x6's on 24" centers, steep pitch (not measured)
- 15' from existing insulated hallway wall to outside wall, roughly 14' vertical at wall to underside of rafters and 0' height where the joists meet the rafters
- attic floor space runs almost 17' parallel to outside wall and interior hallway wall
- existing strong back running lengthwise of floor space across the exact middle of the joist span
- angle bracing supports with an under-rafter cross beam running from the attic side of the hallway wall up to the rafters
- potentially usable floor area of approximately 8'x16' which would have a finished ceiling height of about 5' on the exterior roof-side and approximately 14' on the interior wall (would make a potentially great office, play room, upstairs media room, spare bedroom for occasional guests, etc.)
- there are no dormers on this side of the roof, and our fireplace extends up the exterior wall right in the middle of the lengthwise dimension (does not intrude within this attic space)
- plan is to beef up the structural components to support a 30#/sqft load while opening up the space by removing all existing cross beams and angle supports, install a wall-switched light switch and three receptacles, new 3/4" decking, a door fro the hallway into this attic space (currently only accessible through one bedroom closet by way of a narrow 16" wide walkway into this area), install a one-step-up stairway through the new hallway door onto the elevated trey-ceiled floor joists/decking, and a short but rough one-step down into the upstairs HVAC area.

Work done thus far...
1) Exterior, insulated fiberglass door installed in hallway (we will not convert this room ourselves before selling the house, so I need to maintain current insulation to protect the upstairs from attic heat and winter cold.
2) Crippled rafters installed across from the doorway to host the ends of new 2x8 joists laid between the existing joists so I can create an "on 12" center" joist structure to create the 30# live load rating
3) New joists have been installed to create the boxed cutback double header onto which the new entry stairway will attach (these new joists protrude adjacent to and inside the hallway stud wall for lateral attachment in addition to resting on a 2x4 along the studs at the same elevation as the bottom of the existing joists)

Next Steps (this weekend)
1) Install a temporary strong back across the width of the boxed stairway header (all the way to the next outside joist position) so the cutback joists will not be resting on the trey-ceiling sheet rock when I cut them back to install the new double header
2) Cut back the three joists and install the new double header, leaving the temporary strong back in place until I can begin installing the new decking)
3) Frame in the stair stringers and supports
4) Install the new stair tread and flooring leading to it, as well as the risers and sideboards along either side of the stepway

QUESTIONS & Concerns
1. At the apex of the rafters and joists, I am planning on installing a new strong back for additional "unifying" strength on the outer wall juncture -- I'm not sure this is really necessary, but think it's a good idea -- what do you guys think?

2. At the top of the knee wall, roughly 5-6 feet in from the rafter-joist intersection, I plan to install a full wall-length beam of doubled 2x6 construction as Part A of a two-part replacement for the angled bracing which exists today. Part B will be another double 2x6 beam at a height of about 7-8 feet above the floor, full wall length, resting on the existing end walls. which are load bearing structures. How does this sound to you?

Pictures are below so you can see some of what I'm referring to in the probably confusing explanations above. I'll be taking more pictures in the coming days and will post them as well for additional clarifications.

PLEASE... chime in with insights, questions, & suggestions. I'm all ears.
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Preparing Attic Space for Future Upgrade-doorway.jpg   Preparing Attic Space for Future Upgrade-crippled-rafters.jpg  
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Old 02-15-2018, 08:35 AM   #2
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Re: Preparing Attic Space for Future Upgrade


I would really be grateful for some experienced sanity checks on what I've done and am planning to do on this project.
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Old 02-15-2018, 09:04 AM   #3
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Re: Preparing Attic Space for Future Upgrade


Hi F250, sorry as I skipped over your post, too long. Don't always have the time for online projects and long posts are often headed that way. But I will give it a read.

Before I get into it let me ask, have you or are you going to pull all necessary permits? Converting attic space to living space has some restrictions and I would hate to bait you along into a project you can't (or shouldn't) finish. It is often a difficult subject to bring up but times are changing and very soon if not already local building code offices will be tracking every change and when permits haven't been pulled there can be disastrous results. I have seen entire projects that had to be completely removed plus penalties. They weren't allowed to just bring things up to code.

Off my soap box and I'll wait for your reply.

Bud
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Old 02-15-2018, 09:23 AM   #4
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Re: Preparing Attic Space for Future Upgrade


Sorry but can't put together the words into a visual structure. But that is about the way all posts are.
You seem to know what you're doing, and as a diy, anything else is just a gravy. Unless enthusiasm becomes a money pit.
In NJ and 24" spacing, to me, would be under built. 2x8 span of 15' also. Floor span of 15' would be almost always 2x10. 2x8 roof would be fine.

Your attic looks like a normal attic. Triangle of floor joists and roof rafters. Under built, but maybe that's fine in AL, and fine for light use anywhere. I have to think about snow also. Any bracing, strong backs, knee walls, etc, don't need to be thought of as reinforcements as long as the base structure was designed and built to be stand alone. Anything else is fillers for walls etc. They don't make the floor or roof tighter. Ply or osb would bounce under you anyway. Reinforcements or braces generally have to take the load into something better, such as footing or beams. Otherwise, they are just more weight. Blocks and strongbacks can help but again just more weight if joists and sheathing are under the capacity.
If you have enough room overhead, I would close the rafter bays and such for better venting air flow and install accessible venting fan. It will help esp in your area. Best if 2" continuous from cooler soffit to ridge space.
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Old 02-15-2018, 09:50 AM   #5
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Re: Preparing Attic Space for Future Upgrade


For joists that are SYP or Douglas Fir, in good condition, 7.25 inches tall, 1.5 inches wide, 12 inches on center, and 15 feet long between supports, the deflection calculated is 0.813 inches.

This translates to a deflection of L / 221.

Since the maximum deflection for tile is L / 360, and for natural stone is L / 720, your floor is rated for Sheet Vinyl or wood.
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Old 02-15-2018, 10:20 AM   #6
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Re: Preparing Attic Space for Future Upgrade


Here is an extremely ( must ) good read for anyone wanting to build or change any structure.

https://www.huduser.gov/Publications/pdf/res2000_3.pdf
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Old 02-15-2018, 10:51 AM   #7
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Re: Preparing Attic Space for Future Upgrade


Thanks guys. I realize that long posts are often skipped and overlooked because it can be really really hard to convert written descriptions into visual images. This one is another lengthy one which may not be easily readable on a smart phone. I get that completely. Thanks for taking the time, though!

Answers:
1) Not pulling any permits because I'm actually not doing the conversion. I'm just creating a more stable attic storage space and make it easier for the next buyer to complete the conversion at a minimal cost. We will only enjoy a more easily accessed attic space which is neater and less "rough" (my wife is a city girl, and likes to have her "working spaces" neat, tidy, and cleanable). Also, the space will be able to host my small portable air compressor and my electric tools so I can work out of the attic for any upstairs remodel or repair activities (think solid subfloor and dedicated circuits), and this is a whole lot better than stringing hoses and cords from either the first floor or the basement.

2) I'll pull together a few sketches to better illustrate the existing condition/layout/design and the planned upgrades, but it may be next week while I'm in a remote hotel (central Maine) in the evenings on a business trip before I can dedicate that sketching time.

3) The span tables calculators I've reviewed indicate that 2x8's on 12" centers would be fine for as much as a 15' span while providing a live load rating of 40#/sgft. I know that the knee wall would subtract somewhat from that, but I cannot imagine needing more than a 30# rating for this space to be used as something like an office or play room, so I've been content with that capability.

4) Snow loading is not really much of a concern at all here, though we did get 4" back in early January which technically classifies as something like a once in 50-year event. In other words, it's not a regular loading issue at all.

5) My wife keeps telling me that it's highly unlikely that anyone will ever convert the room. I just want it to create a condition of "readiness" as a helpful selling point when we downsize in the coming 3-4 years. I know that most buyers would not, but someone like me would. Our neighbor across the street loves his similarly finished space as his upstairs office which was finished by the previous owners. For context, the home is about 4200 sqft of finished living space (including the finished half basement), 3 bedrooms/2 full baths upstairs, one bedroom with 1 full and 1 half batch on the main floor, office/bedroom and living area in the basement with half bath and utility room. Shoot, even if it is never converted, it will be a wonderfully nice and neat and ample attic storage space with extremely easy access!

6) The choice of flooring for this room, in our neighborhood, would be roughly 50:50 carpet versus hardwood. Hardwood is what we already have in the hallway and all three bedrooms. No justification for anything like tile or stone up there, and there's really no room to justify more than a half bath in that space.

7) Ventilation space above the blocks at the top of the crippled rafters... I am left with 1-1/2" which should be more than adequate (my opinion, based on the commonly recommendation for 1"). How this ends up will be determined by anyone else who may finish the space in the future.

My goal is increased stability, more nicely semi-finished space, easy access, and convertibility for the next buyers. I make sure that all my work meets or exceeds any code requirements. The few times I've gotten to things which are over my head, I've paid a duly licensed and reputable contractor to do what I cannot. My work will always end up passing an inspection because I do my research up front and am rigid about safety and quality. That's just the way I work.

I'm here to learn some new things to make sure that everything is right. Already, I've learned that I need to include solid blocking, which I neither knew before now nor had planned, but will now include because it's more easily installed now than after the knee wall goes in. When I hit a sticking point, I stop and research and wait until I can come up with a solid and safe solution, and that's why I did not install my boxed in step-well last Sunday... i had to figure out the best way to install the stringers and supports before cutting back and headering the joists at the doorway.

Last edited by F250; 02-15-2018 at 10:54 AM.
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Old 02-16-2018, 08:28 AM   #8
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Re: Preparing Attic Space for Future Upgrade


Point #5. You're thinking way too much. Either finish it or leave it alone. Preparing for easy conversion is not an answer. It will NOT help with selling the house. Buyers will think you left unfinished work or did a hack job of it. If joist to joist (or rafter to rafter) spans are too wide, adding cripples in between is not going to help.
Existing frame pieces can be reinforced but you have to know more than carpentry. I mean that reinforcement has to become more like truss, but that means engineering. Or it becomes money pit.
By your post, you have lot of ideas or see lot of problems. What problems do you see that you want this much preparation? Start with your worst problem and concentrate on fixing it first. Instead of presenting all of your problems, start with one question but with pictures or drawing. Usually hand drawing needs to use a straight edge and try to keep them to scale. Search the web for images close to your problem. Save it and upload here.
BTW don't try to explain your work to a buyer. Appreciating your work is not in their best interest.
BTW #2, if not sure what I mean, try reading other posts. Long posts that try to take care of all problems in a single breathe. See if you can figure it out. Don't include small images of entire architect's plan.
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Last edited by carpdad; 02-16-2018 at 08:31 AM.
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Old 02-16-2018, 02:54 PM   #9
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Re: Preparing Attic Space for Future Upgrade


OK. Points regarding post length are taken. I'll be brief.

"Either finish it or leave it alone."... Seriously? You either haven't read, really thought about, or are completely minimizing the reasons I stated for doing this work!

Our perspectives on an "easy conversion" being a buying/selling point are a matter of philosophy, and each buyer will run a wide range on that one. I'm doing it because I want to and because it is something I would value in a purchase. 'Nuff said on that.

Engineering support? I've got that covered.

The crippled rafters are only to provide a contact/support point at the roof line for the additional 12" spaced joists which are going between the existing 24" spaced joists. They are not meant to enhance any of the roof support structure at all. They are just a place to nail (or screw) one end of the new joists.

Problems? I don't recall having called out any problems beyond having gotten delayed while figuring out how to install the stair stringers, and that is now in hand. What I've written is a set of ideas and plans, and asked for any insights or suggestions if any of it seemed awry. Your first post, carpdad, hit a few of those points, and I thank you for that.

You guys seems to be highly experienced and quite sharp and are great reference touchstones for those of us who don't necessarily do these things on a daily basis. I'm extremely grateful for the service you're providing here in this forum... seriously! At this point, though, there seems to be a serious mismatch between your expectations and how I'm interfacing with you on what I'm doing (and why and how), so I'm going to bow out for now with absolutely no hard feelings about having not meshed up with you all.

I'll check in again if I hit a snag that I can't figure out on my own, and I'll make sure to include pictures and drawings when I do. Until then... keep on helping everyone you can, because I KNOW that you are!!
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