Filling the gap between painted floor boards - Real World Suggestions Please

[Sam Murdoch]

I hate to ask because I'm afraid to start a discussion about all the alternatives/better ways. Nonetheless here is where I am with this project and I am looking for solid, experienced based, advice.

SITUATION - Client floor. Badly laid painted floor - just varying width boards (looks like pine) screwed down - no T&G. Of course there are gaps. My job - lightly sand to clean up and repaint (along with new kitchen cabinets and some tile work).

Question from client - "Please Sam can you fill these gaps with caulking before painting? I know the caulk won't last forever and will likely shrink and maybe even get squeezed out some but it would sure look better for a few years and keep out the draft."As for the draft - you can see the foil faced insulation board between the flooring planks :rolleyes:.

Anyway - she knows the limitations and is not expecting miracles just a modest improvement. Most gaps are 1/16" to an 1/8" and pretty consistent for the 25' of length. Some though are pushing 1/4". I have already introduced the need for backer rod.

ACRYLIC/LATEX or POLYURETHANE ?- I am considering the caulk options. No way am I masking off 25 seams 25' long. At first considered acrylic latex caulk that I would apply and clean as I go along. I think however that a polyurethane would do a better job over the long run - better adhesion and flexibility. However a real pain to clean.

MY PLAN OF ATTACK - Sanding first - there will still be paint on the surface. I am only sanding to clean. Then caulk. Using the latex I would caulk after sanding and wipe clean as I work. I was thinking that well cured poly might be able to go down before I sand and then sand all clean at one time - caulk and paint. This could be a very bad idea.

Yes - I know to clean out all the gaps and vacuum thoroughly. Will be using a Milwaukee battery operated caulking gun for optimum control of the bead size and feed rate.

Looking for recommendation for the right caulk - brand names welcomed as well as type.

Also - would consider some rope type product if anyone can tell me about their experience and satisfaction. There is no money in the budget for fitting wood between the cracks. That procedure has a rash of its own issues in any case and I would be very difficult to persuade on the merits of that option.

Still, I'm asking for advice and so I will listen with an open mind. Thank you for any and all input.

Cheers, Sam

[Mel Fulks]

At the reccomendation of several members here I used some NP-1 on the exterior of my house. It's good, very stretchy,
paintable. I doubt there is anything better.

[Rick Johnston]

Big stretch - a very good paintable caulk. Most caulks shrink, review those properties with whatever you select.

[Graham Wintersgill]

Sam

This is another alternative if you have sawdust available:
http://www.wood-finishes-direct.com/product/manns-mix-and-fill?utm_source=bing&utm_medium=cpc&utm_term=filler+gel&utm_content=Manns+-+Mix+and+Fill&utm_campaign=Brand-Manns

I have also used wood glue mixed with sawdust.

Regards

Graham

[Tom McMahon]

Tile grout, mixed as dry as possible, way easier to apply and clean up, before sanding

[Sam Murdoch]

Tile grout, mixed as dry as possible, way easier to apply and clean up, before sanding

Really - never heard of this. I would think that wood flooring unlike rigid tile will flex/move enough to eventually crack all the grout. Have you done this Tom? With good long term results?

I think the boards on my project are as acclimated/stable as wood floors can be. Had they used a T&G this crack thing would not be an issue.

The wood glue or Lecol sawdust mixture that Graham refers too could have merit if I could find a 30 gal drum of fine sawdust. All I have are thickness planer chips. I will not be sanding this floor to bare wood so the dust generated here could not be used. Solvent based sawdust mixers aren' readily available in the US - too toxic.

Still thinking that a good poly caulk will be as efficient and effective as any other method. I need to locate some NP-1 or some Big Stretch. Time for a trip to a big box I guess. Saturday afternoon shopping :rolleyes:

Thanks for the info everyone.

[Mel Fulks]

Around here np-1 is not in the BORGS ,but they might order it for pick up. We get it from a local supply house.

[Rick Johnston]

Same co the makes big stretch has a product called "conceal" that had wood grain texture in it. Never used it and not likely in the BORG stores. When the gap gets wider that might be a good look.

[Jason Roehl]

We're talking about an interior floor here, with fairly small gaps (1/16"-1/8"). Any good siliconized acrylic latex caulk will do the job just fine and last a good long time. I could probably have that caulked in an hour with a manual (but dripless) caulk gun. If you don't want a mess to clean up, don't put in too much caulk. Cut the tip to have a fairly large opening, larger than the gap, at a 45º angle. Match the speed of your gun movement to the flow rate and vice versa so that you don't have a bunch of excess to wipe up. Smooth it with a wet finger. Smooth, don't dig it out. Keep a wet rag and a bucket of water handy to wipe off your finger often and rinse out the rag occasionally.

I've only run a few hundred miles of caulk in my life...

[Rick Johnston]

Jason, on the wider gaps I'd think the shrinkage might be visible. Easy enough to try and see.

[Jason Roehl]

Jason, on the wider gaps I'd think the shrinkage might be visible. Easy enough to try and see.

Anything that goes in those gaps that is flexible enough to not crack is going to shrink and leave a slight U-shaped profile. A second coat of caulk would alleviate this somewhat.

1/8" is pretty easy for a decent caulk to handle, especially inside where temperatures don't fluctuate much. Plus, if it's a wood plank floor direct over joists, it's probably been around a while, so the wood is thoroughly acclimated, and isn't going to move much.

I wasn't exaggerating a whole lot when I said I've run hundreds of miles of caulk--I was a painting contractor for 19 years.

[Sam Murdoch]

Anything that goes in those gaps that is flexible enough to not crack is going to shrink and leave a slight U-shaped profile. A second coat of caulk would alleviate this somewhat.

1/8" is pretty easy for a decent caulk to handle, especially inside where temperatures don't fluctuate much. Plus, if it's a wood plank floor direct over joists, it's probably been around a while, so the wood is thoroughly acclimated, and isn't going to move much.

I wasn't exaggerating a whole lot when I said I've run hundreds of miles of caulk--I was a painting contractor for 19 years.


Thanks Jason - you are "the guy" I was hoping would give me some feedback. With all due respects to all the rest of you who replied - I thank you too! :) I agree that this floor is well acclimated and stable - all screwed down to the joists. The caulk seems like a decent fix.

I found a local source for Big Stretch and so will likely use that. Now - there are a few seams that are pushing 3/8" wide so I intend to use foam backer rod. Getting backer rod the correct size and length is a challenge - without a road trip or an on line purchase. Can I use some type of rope for this purpose? Cotton clothes line OK or something else? Will Big Stretch in two applications be better than good enough?

Thanks again.

[Jason Roehl]

I've never used anything but backer rod on big gaps. It really does the job well. You want it large enough that it is at least a little bit compressed to fit in the gap, but not so large that you can't get it in there. Length is not an issue either, just fill the gap and break it off when the gap is small enough to go without. You want the backer rod just a little below the surface.

Just buy a couple different diameters of the stuff, I think it typically comes in 25' rolls in bags at the big box stores. I was fortunate to score two unopened boxes (one each of two sizes) at our local Habitat ReStore a few years ago for $10 each--now that I'm out of the biz, I'll probably never use it all.