I am installing a wood subfloor over a concrete floor with 2×4 sleepers in between. I have read that it is best to anchor the sleepers with a combination of construction adhesive and concrete screws. I’ve tried predrilling holes in concrete with my corded drill and an inexpensive masonry bit with mild success. Given the number of screws I’ll need, I wonder if it is worth renting or investing in a hammer drill or do I need to just get a high quality masonry bit and try again? The thought of buying yet another tool is appealing of course but I’m not sure when else I would ever use the hammer function.
– Lyputs
Replies
If I were you, I would bite the bullet and get a hammer drill. Check out the re-conditioned ones...and if so inclined watch ebay and don't foget about CPOBosch. A decent drill can be had for around $140 or so, and given they excell when drilling holes, they are equally fantastic when driving the screws.
For what you are doing buy a cheap/inexpensive hammer drill Harbor Frieght or other tool outlet. It will be as cheap as renting.
The drill bit you have been using will work way better with a hammer drill but you may need several bits to finish the job.
Hammer drill
A hammer drill or rotary hammer will be much faster (and noisier) than your current approach.
Buy something with a cord - not cordless.
The rotary hammer will be the faster of the two - also the more expensive option both for the tool and for the bits.
Note that their are two different families of masonry bits - rotary-only bits (probably what you have now) and percussion bits - both a hammer drill and a rotary hammer will require percussion bits - a rotary-only bit will self destruct in either of these tools as soon as you set the tool in hammering mode.
I like Bosch "Blue Granite" bits for hammer drill / masonry use -- you can usually find packages of 5 bits at a lower price than buying individually in the most likely sizes you will need (5/32" or 3/16"). I find the 5" or 6" lengths the most useful.
I like to drill the holes with a hammer drill, then set the screws with a cordless drill with adjustable torque. Hex heads are generally easier than the Phillips heads but will not be a good choice for the sleepers unless you counterbore the sleepers.
Wear your ear protection! Some gel palmed gloves will be quickly appreciated also.......
Incidently, Tapcon fasteners are labeled for use in ACQ lumber.
Jim
I was thinking of getting a cordless 18v lithium hammer drill for this job. I have about 180 1/4" holes to drill? Would such a drill work comparably to a corded hammer drill?
- Lyptus
NO!
That is EXACTLY the WRONG tool for this job. For that many 1/4" holes, you should be using a rotary hammer.
I really like my Bosch Bulldog 1" SDS.
Each hole will drill in about 3 seconds with that tool.
Easy?
Sure, a hammer drill is better-but the rotary hammer is way much quicker (and easier-you don't want to lean on it like you will with a regular hammer drill. Rent if you have all your pcs cut and just want to spend a couple hours fastening.
For driving, nothing beats an impact driver. Way quicker/easier.
Use the 1/4 inch anchors-;you'll snap the 3/16ths.
W-e-l-l that sort of depends......
....on whether you really want to buy a Lith-ion hammer drill, discover that it is hopelessly slow and hard on batteries - but probably a good drill for other applications in the future. Then buy a corded hammer drill or rotary hammer to actually bore the holes for your sleepers.
DW might be persuaded to allow investment in the "right" tool after several evenings of you banging away in the basement - hammer drills of any description are not known to be pleasing to the ear.
Kind of depends on your domestic situation.
Cordless hammer drill would be about my last choice.
I suspect that you will find residual uses for your hammer drill though probably not as many as a cordless hammer drill used in the rotary-only mode.
Too expensive? Understandable. Consider renting the tool and buying the needed bits.......
Jim
I have very limited experience (one time) with a rotary hammer, but I'd lean toward a Hammer Drill. The Hammer Drill is more versatile. The Hammer Drill drills smoother holes than a rotary hammer, it can also use standard style drill bits and drill regular holes. Also, 1/4 inch holes aren't that wide, I think the Hammer Drill would be fine.
I have a Metabo corded hammer drill and it serves me well. I got it after wearing out a Black and Decker.
Wouldn't a Ramset or other brand of powder actuated fastener be a lot faster and give just as good a job?
And, depending on your personality, it may be a lot more enjoyable.
Well now, already have a Bosch hammer drill and gobs of bits, but for a sleeper floor over concrete with construction adhesive I'd simply use 3/4 thick sleepers (unless the 2x4 is for insulation) and drive hardened 1" concrete nails with a 4# or 6# hand sledge. (maybe 1-1/4" if you can hit straight with a hammer, 1/3/4" nails for 2x4s.)
Did son's basement floor that way, only had to use 2 nails about 10% of the time when the first did not hold. Also did a classroom floor like that.
Practice our swing on a few practice boards and corener of concrete, it does take an accurate, 'healthy' swing, ya cant just 'tap, tap tap " them in.
to adhere or not to adhere
Because my concrete slab was poured just two months ago I think I need to install a vapor barrier. If I install a vapor barrier over the sleepers, I'll potentially trap moisture around the sleepers. Therefore, I'm thinking of laying down a vapor barrier directly on the concrete floor and then screwing the sleepers down on top of it. However, then I won't be able to use construction adhesive to help secure the sleepers. I want the floor to be pretty secure to minimize vibration from woodworking machines. Will 2.5" x 1/4" tapcon screws at 2-ft OC be sufficient without construction adhesive?
- Lyptus
Tapcon recommends
Tapcon anchors require a minimum embedment of 1" and a maximum embedment of 1-3/4".
While 2-1/2" is within the recommended range-I use 3" or 3-1/4"
Yeah, but in this application the screws are just used for "tacking" -- to keep the sleepers from sliding, and to keep them flat until the flooring is done. The full anchoring strength isn't needed.
Dan, you can't go on memory alone..........
You know this place-it's like an amoeba.
"I want the floor to be pretty secure to minimize vibration from woodworking machines. Will 2.5" x 1/4" tapcon screws at 2-ft OC be sufficient without construction adhesive?"
The op's latest post.He's thinking of placing a visq. barrier under the sleepers. to adhere or not to adhere
Once you have a heavy woodworking machine on the floor you don't even need the screws.
Because my concrete slab was poured just two months ago
There should be a poly barrier UNDER the slab. If not, ya forgot something or your contractor did a 'lowball' job on you.
UNDER the slab. If you now put a poly barrier on top the slab, you will rot out your sleepers from condensate from air humidity from the room.
In any case, do NOT put a vapor barrier on the room (heated/warm) side of cold concrete if it will be in contact with wood.
Location of vapor barrier
The contractor did place a vapor barrier under the slab but I've read in Fine Woodworking that one should also place one over the slab to prevent excessive humidity from building up in the shop. So I was proposing putting a vapor barrier under the sleepers to keep moisture fully out of the shop and away from all contact with wood. Would this work? I just don't know if this will create any sort of mold or other problems with the concrete slab.
- Lyptus
IMO, FWW or whoever wrote that is wrong.
It don't happen often
But I'll have to agree with the old guy from the State of Washington.
And of course we both could be wrong by some chemist that has the figures.
But, if the concrete is kept dry from the bottom and the sides-and has cured out (not immediate by any means) .......
then the slab will be dry. More visqueen will do nothing.
This assuming the finishers that placed the concrete weren't in a hurry and poked a bunch of holes in the plastic.
But still the sleepers should be treated or there should be some moisture barrier between them and the crete.