I recently purchased a home in sunny Florida that includes an 8 ft wide and 12 ft deep golf cart garage. I am using the area for my shop because I don’t golf. Since the ceiling is quite high, I want to turn the space above the garage doors tracks and opener mechanism into a loft storage area. The structure will be attached to two concrete block walls at either end of the 12 ft dimension. I need assistance to determine: 1. the proper size joists I should use to span a 12 ft distance and support a load of mainly boxes of books; 2. the spacing of the joists and; 3. how to attach them to the concrete block walls. With regard to the last item, at one end there are 2 vertical 2x6s that support the garage door tracks that extend from the floor to about 12 inches above the garage door hardware. These are bolted to the concrete block wall that forms the front of the garage. Can I attached one end of the loft platform to them? Also, I assume that the floor of the loft should be 3/4 inch plywood.
Thanks for your help!
Jim in Palm Beach Gardens
Replies
I'm trying to picture this...Is the door in an 8' wall or a 12' wall? Is there a way to span the 8' dimension rather than the 12? For a 12' span, I think I'd go with 2x8 16" o.c. hung by joist hangers on ledgers lagged with anchors in the block and your 3/4 plywood decking. How do you plan to get up there?
Al Mollitor, Sharon MA
"I'm trying to picture this..."
MOJO,
Yeah, me too. Again, one of those times where the poster should post a pic if possible. A PICTURE IS WORTH A THOUSAND WORDS, plus he'd get more feedback.
Jon
Hi Jim.
If you have plenty of headroom after setting your joists on top of the concrete walls, then by no means go the ledger route as earlier suggested. Also, according to my span tables book, 2x8 placed 16 inch OC cannot adequately support your proposed 12 foot span; least not with N0.1 or N0.2 grade nominal joist lumber.
Now if you were spanning the 8ft width, you could possibly get by with 2x8s; but that was not what you were after...right?
So, if using nominal 2x lumber ( either Doug Fir or Spruce-Pine-Fir) you should use nothing less than a 2x10 with a 16inch OC spacing.
Do indeed use 3/4 plywood for your decking. Install plywood perpendicular to the joists and stagger your seams. Use adhesive and 2 inch drywall screws or 6 penny ring nails ( nails are easier, but I like screws). Check out Advantech T&G plywood if your local lumber stores carry it. It resembles OSB but is really good stuff. T&G will give you a stiffer floor, and in my area, the Advantech was cheaper than my local supplier's regular brand of plywood...this may be the case in your area too and may save you some money. T&G is not necessary for your storage floor, but is an added bonus if the price is right...if price is not right, don't use T&G.
Bottom line about attaching joists to concrete walls....you really don't need to. Once the flooring is installed, the joists won't roll and the floor will be plenty stable for a storage floor.
Set your joists on the wall in place at both ends. Take a 2X4 and lay out for 16 inch centers like you would normally do for a stud wall. Attach this 2X4 to the bottom of each joist. This 2x should be held tight against the concrete wall when you attach this to the bottom of the floor joists. Do the same thing at the other end of the 12 ft span...layout another 2X4 and attach it to bottom of joists while holding 2x tight against other wall. After doing this, the joists are now properly spaced and "locked in" so it cannot travel forward or backwards off the concrete wall. The joists cannot roll over now either, making it safe to lay up and attach the plywood decking.
If you really want to attach the joists to the wall, simply lay some 2X cleats on top of the wall and attach using tapcon screws or using a Powder actuated stud gun. Once the cleats are secured, attach the joists to the cleats with screws or nails.
LOL.
Davo
I'd use 2x10 at 16" OC in hangers to ledgers. More support for heavy items like books is easier & cheaper now. Spannig the 8' distance is preferable. 3/4 play is a good choice.
The access question is very apt. After putting this "ceiling" into your shop space, make sure you give it a good coat of white paint. Have you thought about getting light into the two new spaces (above and below the loft). Under the garage door is already tricky--but makign a shadow from existing overhead lights, or creating a dark corner in the back of the loft will be a little unpleasant (am there, do that).
In my first post, I was assuming that the concrete block wall had enough room for your joists to simply sit on top of it. If so, avoid the ledger system.......but, if you need to attach to the face of the block wall, then a ledger system with joist hangers is the best way.
for infrequent access to your loft, either build a "stair ladder" or install an attic acces stle ladder system. If you plan on going to the loft all the time, plan on building a stairway ...usually built along one wall for giving you the most un-interrupted space down below.
As mentioned, lighting is very important. Plan for that.
Davo
What are you storing? Your Christmas decorations or your Chevy short block collection?
_______________________
Tool Donations Sought
I'm matching tool donors to a church mission to Haiti - we're shipping a bus converted to a medical facility in (now it looks like) April and can fill it with clothes, tools and all sorts of stuff needed in that poorest of all countries. A few hand tools or power tools can provide a livelihood for an otherwise destitute family. Please email me if you have tools to donate.
Thanks to Jeff and David and Jim and Rich and Steven and Mark and Jason and Shep and Jen and Mike and Joe and Bill and Ken for their offers!
Several donations have arrived! Thanks and God bless!
He has thousands of copies of that new best seller by Bob Walker, "How to get to the point"
;)
So it needs to be stout.
Welcome to the
Taunton University of Knowledge
FHB Campus at Breaktime.
where
Excellence is its own reward!
Let me clarify a couple things about the space in which I want to build this loft. The golf cart garage area is 8' w x12' d x 12' h. This rectangular area has walls on 3 sides, two 8' and one 12', with the fourth 12' side open to a 2 car garage. The overhead door is located on one of the 8' walls. I need to hang the joists between the two 8' walls so that the overhead door tracks and opener mechanism will fit between the joists (the joists and tracks will be parallel). The top of the floor will be 9' from the floor providing me with a 3' high space in which I will store boxes of books, christmas decorations and other household stuff but no small block Chevies. I plan to use a step ladder to access the area from the side open to the garage. Light will be provided by a huge window already in place on the 12' wall and by fluorescent fixtures I plan to install between the joists.
It sounds like I should attach ledger boards to both 8' walls and hang 2x10 joists. Any other thoughts? Thanks much for all of the quick replies.
My floor joist span table for 40 lb. per sq. ft. live load, 16" spacing says 2x8 so. pine should span about 12'-10". Since this will be a storage area with only 3' to 4' of head room, I'd feel safe with 2x8's. I'd pay most attention to how the ledger was attached to the walls.
Be sure to lay things out with the door UP. That extra inch or two needed for the swing of the door can surprise you!
Al Mollitor, Sharon MA
Thanks, AL, for all of the info, especially the heads up about the door swing. I'll measure carefully.
I wouldn't want to be climbing a step ladder 9 feet carrying 50 pound boxes of books. Think about installing an attic stair. Doesn't take any more room than the hatch to get into the loft and they don't fall over
good point. safety first. thanks!
I will second both the 2x8 sizing @ 16" oc with hangers and the loft ladder but you'll need to double up the joists on either side of wherre you header off for it.
Attaching ledgers is the main structural concern. In concrete walls I would use 1/2" wedge bolts. I have no idea what would be best for block walls though.
You mention having the openner sit BETWEEN the joists. Be sure to plan that out precisely. I see potential problems there..
Welcome to the
Taunton University of Knowledge
FHB Campus at Breaktime.
where
Excellence is its own reward!
Rather than one of those rickity fold-up stairs, you could make your own. I'm thinking about doing this for my garage...a simple ladder/stairs made from 2x6's that's hinged to a ceiling joist and raised and lowered with a rope and pully system. Since it's a garage, it doesn't have to be pretty or airtight.
Al Mollitor, Sharon MA
Thanks for all of the suggestions and great ideas. I'm going to start making some plans.
Since you are 3' down from the top of the wall I would feel safe using tapcons through the ledger board and into the block at 16 or 24" staggered spacing and costruction adhesive liberally applied.
The ledger boards need to be treated lumber since they will be in contact with a masonary wall. This opens another can of worms if you get the new treated stuff. Anchors, joist hangers, and nails all have to be better galvanized stuff than you find in you area. Seems like the hardware supply for this stuff hasn't quite caught up to the supply of the new treated lumber in all areas yet.
Dave
Dave,
I respectfully disagree. If he is using 2x8 joists there is no way I would spec tapcons into the block. Especially at the spacing that you suggest. As to the treated lumber, I would probably stick with spf rather than deal with the corrosion issues. Or maybe he could find some leftover 2x8's, 2x10's, or 2x12's to use as the ledger.
Jon Blakemore
Jon, I figured tapcon and construction adhesive because they will provide nearly twice the shear value he needs at 60 pounds per square foot loading and 20 psf dead load. Withdrawal is not much of an issue b/c the loft is captured between blok wall.
According to Tapcons web site a 1/4" tapCon embbeded 1 3/4" in a concrete block has a pull out value of 801 lbs. and a shear value of 1059 lbs. With 7 screws per 8' ledger they will carry the load.
I think you recommended 2x8 @ 16" o.c. which is for a 40 lb live load. Using wedge anchors in hollow masonary blocks is not a good idea, IMHO. Through bolting would be the optimum choice, but then you have either bolt heads or nuts and washer exposed and ugly on the outside of your building. I have also used toogle in hollw massonary units, but was never comfortable with them because of the blow out inside the block when drilling the holes.
He did not say what type of roof is on the building, but I and guessing flat. With only 3' of storage space up there I would hope he doesn't exceed the nearly 2 tons of loading, the loft can safetly carry.
I am completely open to corrections on my numbers, so have at it. I'll learn something new today.
Dave
It's good to hear Tapcons would carry the load because they are also easy to install.
If there was a concern, a few vertical 2x's from ledger to floor would be a sleep aid.
Al Mollitor, Sharon MA
PS: I don't know about anyone else, but we've had to coldest January in over a century. A trip to Florida is starting to sound good right about now...
Dave,
I still feel a bit wary about the Tapcons, but after seeing your numbers I am more open to the idea. I think the biggest problem I have with them is not the shear value of the fastener but the strength of the block and mortar. As you mentioned your reservations with toggles blowing out the wall, I would be concerned about the mortar not being up to the task of supporting 1,059 lbs. I did not expect the shear to be that high, so I think you could apply a generous safety factor and add a few extra Tapcon's in and then sleep well at night. If he installed two per joist bay that would take 24, so a box of 25 would be perfect...
Jon Blakemore
I use a lot of TapCons in hollow masonary units, but not for those kinds of loads. I try even with light loads to drill at the web members of the bolck. If using a 1 3/4" tapcon I drill 2" per the instructions. You can only do this if you land the hole on the thick web of the block. Otherwise you blow through into the hollow part and get nearly zeroe strength. For the more permanent attachments we add construction adhesive also. I don't know how much it increases pull away or shear, but I sleep better with it there<g>.
I was suprized at the pullout and shear numbers for Tapcons too, particularly in hollow masonary units.
Dave
I am a firm believer in Tapcons. I am also a firm believer that some folks can get themselves in a false sense of security with them. The problem I see with some is not using the proper drill bit or not keeping the drill steady and getting an oversize hole. Also with the proliferation of impact drivers and higher voltage cordless drills some people over tighten without totally stripping. I use the tapcon driver which pretty well eliminates the latter problem.
Just like most thing we do, if done right they are super. My BIL has a bumper sticker in his shop " when you finally make something idiot proof, they will come up with a new idiot".
By the way this was not meant to disagree with you.
Let me jump back in with a few thoughts here.
First, he qupted shear values for 1/4" Tapcons. The more widely stocked variety in most hardwares that I see is the 3/16" variety which is likely to have just over half the shear value. I don't have the book though. So be sure to use 1/4" size or double up[ on the number used.
The other doubt I have about them for this is that the values quoted is with 1-3/4" in the block. The typical wall of a concrete block is only about a one inch section.
Construction adhesive has less shear strength than most give it credit for.
The code requirement of PT fgor masonry contact has little to do with distance from ground. One reason is that Concrete is permeable and that the thermal mass is different from lumber. So masonry will bring on condensation far before wood. The lumber in contact with it will absorb that moisture with potential for rot and insect trouble. Florida has a lot of humidity so the condensation will present itself in this basicly exterior installation It may also wick moisture from rain on exterior surfaces of the wall.
evidence to the contrary lacking, I would be likely to install with Tapcons 1/4" x 3" at about 2 for every 14-16" and staple tarpaper to the back side of regular dimension framing lumber to isolate it from contact with the masonry..
Welcome to the
Taunton University of Knowledge
FHB Campus at Breaktime.
where
Excellence is its own reward!
Check out their site, they have two lines of SS tapcons (not needed for this project though).
http://www.itwbuildex.com/scotstap.htm
This is is standard tapcon:
Test Number CH3748/ Pittsburgh Testing Laboratories
Anchor Diameter
1" Embedment
1-1/4" Embedment
1-1/2" Embedment
1-3/4" Embedment
3/16" Dia.
209 lbs.
357 lbs.
468 lbs.
547 lbs.
1/4" Dia.
406 lbs.
615 lbs.
851 lbs.
984 lbs.
Shear Strength
Test Number CH3932/ Pittsburgh Testing Laboratories
Anchor Diameter
Anchor Embedment
(3145 PSI) Hard Rock Concrete
Lightweight Hollow Block
3/16" Dia.
1-1/4"
852 lbs.
731 lbs.
1/4" Dia.
1-1/4"
1604 lbs.
1058 lbs.
Look what I found on this (tapcon)site:
View Image
Edited 1/31/2004 5:40:15 PM ET by RASCONC
Man, I couldn't agree more.
I use a cordless drill with the torque setting real low. I finish driving them by hand when the drill clutches out. Even then I have stripped my share from wobbeling out the hole.
I love you BIL bumper sticker. I have used the first half of it for years. Now I have the other half. Thanks,
Dave
Thanks, by the was I did not mean the bumper sticker comment toward the original poster in any way.
As I said in my first post I would use some 5/8 hot dips, at least a few as the old belt and suspenders approach if I did use tapcons. But then I have a Bosch Bulldog and the next step up as well as a bucket load of bits.
Since this is inside and 8 or so feet off the ground, I don't think rot is a big worry and PT lumber probably isn't necessary. Perhaps a layer of felt between the ledger and block would do. Also, if PT was used, since this is inside and the lumber would stay dry, I think the corrosion caused by the salts in the chemicals mught be reduced, but I'd still go with the heavy-galvanized hardware.
Al Mollitor, Sharon MA
Just what I was going to say. I would cut a strip of 15#felt and staple it to back of ledger. I would put a few tapcons in to scab it up and put 5/8 galvanized carriage bolts through on whatever centers are called out if it were a deck ledger. I believe Simpson has some large washer type discs if it makes you feel better for the outside. It is going to be in shear so there is no real pullout load as i see it.
I completely agree with you, but my code book does not stipulate height off floor or exposure as an exception. He may or may not have this loft inspected, but at some later date he may sell the place. A good home inspector would catch this as a code violation. No big deal if you are willing to take negotiate a lower selling price because of not spending a few extra bucks when he builds it.
The felt paper behind the ledger is an excellent idea. I did not reccomend it, because I reccomended construction adhesives with fasteners.
In another thread I kinda got on a stump about the over use of treated lumber, but no matter what I think, I gotta build to the code.
Dave
Dave:
Just to be clear: Are you saying code would require PT ledgers inside because they are in contact with concrete, similar to a mud sill? I hadn't considered that. In that case PT ledgers and adhesive would be the way to go. Maybe the blue stuff on Tapcon would protect them from the ACQ.
Al Mollitor, Sharon MA
It is 3 deg. here today or I would run down to the truck and get my code book. KY residential code does not differentiate between mud sill and ledger boards. It just says masonary contact.
That is the stuff that frost my nuggets about some of the PT lumber requirements. We are requried to use PT lumber for plates in finished basements or any slab on grade. No soil contact, no weather exposure, and very little risk of termites, but the inspectors will red tag it if is not PT.
Don't know if the blue coating on TapCons are enough protection for ACQ. They do make a stainless TapCon that has a clear/yellowish coating on it. That would be my choice.
I'll e-mail TapCon and see how they respond to the ACQ question. I would hope they are addressing this issue too.
Dave