I want to lay a wooden floor in a small space (2.1 x 1.6 m) where the substrate consists of a reasonably newly cast concrete slab (4 months indoors).
The concrete slab serves as a landing in a staircase and has not been equipped with underfloor heating; however, the space under the landing is heated. The wooden floor is made of tongue-and-groove solid "planks" in elm.
The recommendation I received is to put joists on the concrete floor and screw the planks into the joists at a 45-degree angle through the tongue.
My problem is that I want to minimize the "height" of the floor, and since the planks themselves are already 14 mm, it would be way too high if, say, a 20 mm joist was placed underneath.
Ideally, I would just glue the wooden floor to the concrete, but then you might have problems with moisture and risk the wood warping, or is there some smart glue or other product that can be used? Someone I asked mentioned something about "technical silicone"...
So, is there a smart way to minimize the "construction height" while avoiding the moisture problems caused by the concrete?
The concrete slab serves as a landing in a staircase and has not been equipped with underfloor heating; however, the space under the landing is heated. The wooden floor is made of tongue-and-groove solid "planks" in elm.
The recommendation I received is to put joists on the concrete floor and screw the planks into the joists at a 45-degree angle through the tongue.
My problem is that I want to minimize the "height" of the floor, and since the planks themselves are already 14 mm, it would be way too high if, say, a 20 mm joist was placed underneath.
Ideally, I would just glue the wooden floor to the concrete, but then you might have problems with moisture and risk the wood warping, or is there some smart glue or other product that can be used? Someone I asked mentioned something about "technical silicone"...
So, is there a smart way to minimize the "construction height" while avoiding the moisture problems caused by the concrete?
http://www.isola.se/kampanjStop.asp Lay your floorboards in the same way as a parquet floor.
One can lay age-resistant plastic and then a type of rubber strips across the future floor's direction, and then drill and screw the floor down through the tongue with special concrete screws. You screw where the rubber strips are placed, so it becomes tight.
It has been a while since I laid such a floor, but the system came from Baseco, and thus accompanied their floor. But it is surely possible to get the strips and screws from somewhere else. And no, no plugs are needed, you drive the screws directly into the concrete. However, you will go through a lot of four-millimeter SDS drill bits, they break all the time..
Here are the assembly instructions:
http://www.baseco.se/pdf/montering_betong.pdf
Here are the assembly instructions:
http://www.baseco.se/pdf/montering_betong.pdf
Quote:
Originally posted by Bror
http://www.isola.se/kampanjStop.asp Lay your floorboards in the same way as a parquet floor.
That carpet looked simple, but please explain more for a beginner. I assume you roll out the carpet on the concrete, but what happens next?
First, you lay a layer of Platon ventitex to avoid clapper noise, then you roll out the Platon floor membrane, which provides an air gap against the concrete so that any moisture can be ventilated out. Now the base for the floorboards is ready. You glue the floorboards in the tongue and groove as a floating floor with a gap of at least 5 mm against the walls. The floorboards must be straight and flat for the best result. Use a ventilated skirting board against the walls.
Originally posted by Bror
http://www.isola.se/kampanjStop.asp Lay your floorboards in the same way as a parquet floor.
That carpet looked simple, but please explain more for a beginner. I assume you roll out the carpet on the concrete, but what happens next?
First, you lay a layer of Platon ventitex to avoid clapper noise, then you roll out the Platon floor membrane, which provides an air gap against the concrete so that any moisture can be ventilated out. Now the base for the floorboards is ready. You glue the floorboards in the tongue and groove as a floating floor with a gap of at least 5 mm against the walls. The floorboards must be straight and flat for the best result. Use a ventilated skirting board against the walls.
Regarding my previous post, it might be a bit of an exaggeration with Platon since no moisture can come from below like it can with a slab on grade.
If the floorboards are of such quality that they can be laid as a floating floor, you can do the following: plastic foil, felt paper, and then glue the floorboards together at the tongue and groove. You might need to make some arrangement to press the boards together when you glue to ensure tight joints. If the boards are a bit warped and skewed, jon_hs's suggestion might be a good alternative.
If the floorboards are of such quality that they can be laid as a floating floor, you can do the following: plastic foil, felt paper, and then glue the floorboards together at the tongue and groove. You might need to make some arrangement to press the boards together when you glue to ensure tight joints. If the boards are a bit warped and skewed, jon_hs's suggestion might be a good alternative.
I have now carefully examined the boards and discovered the following:
- It is groove + loose tongue rather than groove + fixed tongue.
- The boards are not completely flat but slightly concave when viewed from above.
- Tested a plank and there is a small gap when pressed together (by hand).
Can the same installation method be used for groove + loose tongue as for groove + fixed tongue? I assume screwing (jonh's method) is the way to go since the boards are not completely flat...
- It is groove + loose tongue rather than groove + fixed tongue.
- The boards are not completely flat but slightly concave when viewed from above.
- Tested a plank and there is a small gap when pressed together (by hand).
Can the same installation method be used for groove + loose tongue as for groove + fixed tongue? I assume screwing (jonh's method) is the way to go since the boards are not completely flat...
I looked up jon_h's tips about Baseco's products and it sounded smart and good, but unfortunately, they were quite costly. Especially considering that I have to buy whole packages of everything even though I'm only going to lay 4-5 m2 of flooring. In total, screws and strips would cost 1000 kronor!
Got a suggestion from another source:
Screw plywood (maybe 8 mm thick - regular plywood?) to the concrete with countersunk screws and plugs.
Possibly lay a foam mat (impact sound insulation) under the plywood.
Glue the planks to the plywood with wood glue. Place weights on it and let it dry.
Sounds cheap and fairly simple, but gives a build height of maybe an extra 10 mm in addition to the floor's 22 mm.
Are there more options or should I go with the smart expensive option, according to the saying that you get what you pay for?
Got a suggestion from another source:
Screw plywood (maybe 8 mm thick - regular plywood?) to the concrete with countersunk screws and plugs.
Possibly lay a foam mat (impact sound insulation) under the plywood.
Glue the planks to the plywood with wood glue. Place weights on it and let it dry.
Sounds cheap and fairly simple, but gives a build height of maybe an extra 10 mm in addition to the floor's 22 mm.
Are there more options or should I go with the smart expensive option, according to the saying that you get what you pay for?
Why not glue Mosaic parquet directly to the concrete?
Mosaic parquet is glued with flexible adhesive directly onto concrete floors and is 8 mm thick solid wood that is laid on a net similar to glass mosaic. These floors become very resistant to wear and are used, among other things, in public environments.
http://www.woodia.se/produkter-mosaikparkett.php?id_floor_group=8
/Patrik
Mosaic parquet is glued with flexible adhesive directly onto concrete floors and is 8 mm thick solid wood that is laid on a net similar to glass mosaic. These floors become very resistant to wear and are used, among other things, in public environments.
http://www.woodia.se/produkter-mosaikparkett.php?id_floor_group=8
/Patrik
If the boards/planks are not completely flat, they are probably incorrectly manufactured.zachris said:
Look at the end of a plank. If the annual rings are positioned so that you have the heartwood side up (the side towards the center of the tree trunk), the wood will bend in the opposite direction because the annual rings strive to straighten out due to the fact that the cells in the sapwood are larger and therefore dry faster than on the heartwood side. This causes the heartwood side to bulge (and that is the side you want/should have facing up, but the sawmills sometimes ignore checking which is the heartwood side). To counteract this, the planks should be scored with several shallow and parallel saw cuts along the annual rings to counter this tendency. This keeps the boards flat. (You can create such grooves yourself. Max 1/3 of the thickness in depth. First, you need to lay them outdoors with spacers in between under a tarpaulin (preferably with additional weight), so they absorb moisture and straighten out. Then saw.)
To lay a solid wood floor with the lowest possible building height, the method of laying it floating is best. That is, glue the joints without nailing (or screwing) it to the substrate and with a good gap to the walls and other fixed objects. Then the wood can absorb moisture, swell, and then dry and contract again (which it does every year; in the fall, it dries when the heating comes on, in spring, it swells when the humidity rises during summer) without cracking in the joints.
To keep the floor together (considering that even heavy objects on the floor prevent movement), the method used by Holmsund golv (the steel band method) is recommended. This involves laying steel bands of some kind under the boards perpendicular to the length direction (cc 1-1½ meters), which are attached to the first and last board. Between the boards and the concrete, you need a slip layer of some kind, and since you claim that moisture insulation is not needed, you can probably use a plastic film + a gray felt paper. (Personally, I would lay blue Platon and snap-on foil on it, not the other way around.)
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Byggaren
Oh dear, that doesn't sound good. Maybe I should simply file a complaint about them? I'll check the thing with the annual rings first...imported_Byggaren said:
One thing that's struck me is that there seem to be different definitions of solid wood flooring, or I've misunderstood everything. My floorboards consist of solid wood on the top side (about 10 mm) and some kind of "plywood" on the underside (about 12 mm). Is this a solid floor, or is a solid floor only made of wood (no plywood)?
Interesting. I've actually received that suggestion from others I've asked as well.
How do you attach the steel bands? Would regular "hålband" be sufficient?
Yes, it is moisture insulation I need - if I said anything else, I must have been rambling.
No. Solid wood flooring is made from the same type of wood all the way through (sometimes also called homogeneous wood flooring).zachris said:
What you have received is a veneer with a backing carrier, in this case apparently plywood. Then there should be no need for grooves on the backside since plywood is cross-bonded and thus dimensionally stable/restrained and there are no growth rings visible at the ends.
What might have happened with the plywood's dimensional stability is that the counter-lamination that should be on the free side of the plywood has been omitted since tensile forces arise in the glue joint between the veneer and plywood due to different expansion. (You can see this most easily if the plywood is visible or covered with some kind of film/paper.)
I have to refer you to Holmsund's flooring in Holmsund. However, the factory burned down in 1968 and I don't know if it's been rebuilt or bought by someone else. The steel band itself is more of the type used in packing large wooden crates. Punch holes are too thick. You attach it on the underside of the first board with special thick FH nails/screws. In the end of the last board's underside. Then you have to measure and cut the band first and then fix it and after that stand the next-to-last board up and push both it and the last board simultaneously into the joint to get enough tension on the band. Much like when laying parquet flooring at the end.zachris said:
In that case, blue Platon sheet + clapper film and then the boards. Also use Syninge ventilated floor skirting along the walls to ventilate the space under the floor and don't let the floor and Platon sheet go all the way out to the walls. At least a 5 mm gap is recommended.zachris said:
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Builder
Thank you for all the information and valuable tips! I finally chose to install the floor according to the method suggested by jon_h, and the result turned out quite well. If anyone is interested in seeing some pictures of the installation and the final result, they are available in the following blog post:
http://lundhagen.blogspot.com/2008/01/sista-betonggolvet-borta.html
http://lundhagen.blogspot.com/2008/01/sista-betonggolvet-borta.html