‚Äč

website security

Ask The Doc A Question!

Question:

............... The home has hardwood oak floors throughout the first and second floors. The bungalow was built in 1929, and the floors are probably original. They have been refinished before but seem to be in good enough shape to sand and coat, that is to say the boards are not overly thin by my estimation. I think the only real problem is that there are some large, long gaps especially on the first floor but not exclusively. Some gaps are as much as a 1/4 of a inch. Also, as I had mentioned in my previous e-mail, the gaps, on the whole, seem to only appear every five courses, that is to say every five boards (the boards are typical width, not wider than I'd say 3 inches). I know that the fluctuation in temperatures and especially humidity play a large roll(we live in New England, Rhode Island, USA), but do I have any recourse....................

Kevin

Answer:



Dear Kevin

A home built before WW II would have wide pine planks as a subfloor. They were installed "air dried", when the house was built. If a good builder had planned for a hardwood floor on top of this pine subfloor he would have laid the pine planks on a diagonal to the floor joists. But in a lot of cases the house would have been sold without the hardwood, and in this case the builders back then would have installed a tongue and groove pine plank at right angles to the joist. And later the first owners would have installed hardwood strip floor on top of the pine boards.

The mistake that the hardwood mechanics made was to install the hardwood in the same direction as the softwood subfloor. So, even though the hardwood was kiln dried the subfloor boards would have begun to do their final drying only as the house was heated over the first winter. As the pine subfloor shrunk, it would have caused larger gaps in the hardwood nailed to it. And it is very typical that this would happen every 5" corresponding to the width of the pine boards.

So, there is no way of getting that floor tight again, except to remove the entire hardwood floor, renail the now loose pine subfloor back to the joist and re-install the old hardwood, or install a new hardwood floor. And this time the new or old floor will need to be installed opposing the old pine floor boards. I'll take a little excerpt out of the "squeaks article" to show you how to do this now.

....................You remove an old floor the opposite way it went in. Start at the far end of the room where the last few boards were laid. They will have their tongues pointing toward the wall. The last 2-3 rows will be face nailed. You will only have to crack one board in half ( with a chisel and mallet ) in the last row to remove it. Then use a cat's paw restorer at http://www.leevalley.com/wood/page.asp?SID=3D&ccurrency=3D1&page=3D32014&category=3D1,43456,43399

This tool will gently remove the boards without damaging them. Try to scoot the thin edge of the catspaw under where the floor is nailed, and pry just a little at a time. Once you work backwards into the room and get some maneuvering space you can use a larger tool : http://www.leevalley.com/wood/page.asp?SID=3D&ccurrency=3D1&page=3D32015&category=3D1,43456,43399

The renovator bar will ease up the most stubborn boards. Once you have the whole floor removed, re-nail and repair the subfloor, so that when the hardwood goes back, it will be squeak free. Re-nail the subfloor with the spiral spikes that are at least 3 times the thickness of the subfloor. A one inch thick pine plank subfloor needs 3=94 nails to refasten it to the joists. A subfloor board 4-6=94 wide needs two nails on EVERY joist. Wider subfloor boards need 3 or even 4 nails to firm them up. This is the last chance you have to fix the subfloor.........................

So, Kevin this is the best way to deal with this floor, but if this seems too daunting you could try to save the floor as is. First you will need to renail the hardwood floor back to the joist, to keep the floor from moving. This is because I'm going to suggest you slurry fill the floor. So I'm going to send another excerpt from that same article on how to re-nail it first :

................Once you have marked out all the joists with the chalk line, determine which side of the hardwood strip is the tongue side. You will want to pre-drill or nail spin a 3" spiral finishing nail, so that this nail goes through the tongue side of the hardwood floor board through the subfloor, and penetrates the joist quite solidly. Nail spinners are a must and are available at www.leevalley.com ; Prod. #99K20.01. The nail should be spun in at about a 45 degree angle, the same as a new floor installation. This 3" nail should be only used for

3/4" thick floors, use shorter ones for thinner strip floors. A 2 1/2" nail should be used for 1/2" and 3/8=94 hardwood strip floor so as not to crack the tongues. The nail spinner works wonders for this application,I don't do repairs or installations without it. But be sure to use the spiral type nail in this use.................

Now once the floor is solidly renailed you can slurry fill the floor.There would be about three choices of the filler. The best and longest lasting would be a good quality oil based polyurethane varnish mixed with fine maple floor edger sanding dust. Now the key here is the dust, is has to be very light in color (maple is best) and very fine like talcum powder (and clean). You might persuade a local floor mechanic to sell you some. But as he may save it for his own jobs it may be hard to find. The next best mixture is the red oak floor edger dust and lacquer finish mix. Not quite as flexible but faster drying and easier to find the dust. And the last choice would be those pre-mixed filler buckets meant for hardwood floor filling. This is the worst because of the poor adhesion to the floor gaps, and will in most cases crack out in just a few years. But it's available at most wood floor trade shops. So in any case, trowel in this filler across the whole floor, and for the poly based, wait a week for it to dry and then have the floor sanded professionally. But do the finishing yourself. Finish with oil based poly as I describe in the "Applying poly without the bubbles" article.

The lacquer/dust mixture will dry in two days, and be ready for resanding, and the water based pre-mixed should dry over night in a warm house. I use a steel drywall trowel and go over the floor twice when filling. On a really rough old floor I will do the coarse sanding first then the slurry fill, but this may not be needed your case. Try to remove most of the excess filler from the surface as you trowel so you the floor mechanic doesn't have a hard time sanding it off. Some filler will pop out during the sanding process. But only with the lacquer and water base can you touch up the filler as you are sanding (they both dry fast)

The poly/maple dust will turn a little darker than the floor, but you can lighten it as you are mixing it by adding whiting (powdered chalk), and some universal tints. The lacquer/oak dust is about the correct color, and the water based filler come in a few pre-mixed colors, but choose one just a tad darker than the final finished color of the wood. You can determine what the final floor color is by sanding the floor to the bare wood in a small area, and splashing some paint thinner on the exposed wood. Try to get the filler color right, or you will have a really striped floor. This would be a good project for about mid spring when the floor is at it's mean EMC (equilibrium moisture content). Once you have the floor filled, sanded and finished try to keep the RH indoors within a narrow range (40-60% would be ideal). Air condition in summer or heat and humidify all winter to achieve this and the filler might stay in. It's important to keep the basement or crawl space in the same RH, then neither subfloor or finished floor will move.

Do Not try the glue and sawdust filler, or glue and stained rope filler, as suggest by some pros. You should never have the wood floor edge glued in any way, as this will tear boards in half during larger humidity shifts. I know I've seen it happen.

Sorry to take so long but I thought I would show you all the methods from best to worst. After all you paid for it.

Any more questions you may have on this subject or clarifications of your original question feel free to write again at no cost. I hope you have enjoyed this personal service, real human responses are the best.

As always your Most humble servant, Joseph, the Wood Floor Doctor.

You may also find these articles helpful:

1. Case Study Wood Flooring - Wrong Way Floors

2. Case Study Wood Flooring - Wrong Way Floors Conculded

3. How To Sand Wood Floors Without Leaving Machine Marks

4. Hydronic heating under your wood floors

5. How To Take Care Of Your Health And Safety when Installing, Finishing, Repairing or Cleaning your wood floors