Ants Coming Through Gaps In Old Pine Floorboards


We are the caretakers of an old farmhouse built around 1883. We can not invest a lot of money restoring the old wooden floors and the board of directors does not have a lot of money for the upkeep of the house. Sad but true so money is a concern. Labor is not. So here is my question..the foors have gaps between them and now that the weather is warming, large ants are coming into the living room and we assume through the flooring. We do not want to use any harsh pesticides under the house to get rid of the ants and that would be an ongoing task as well. Is there a way to seal these old floors, not sure how to deal with the gaps. Gaps are no more than 1/8 to 1/4 inch in size. Debbie


Dear Debbie

It’s quite normal for old pine floorboards to have gaps in them, and I really never suggest filling them especially from above. You don’t want to change the character of these old wide boards, because filling the floor from above usually (but not always) means a sanding and finishing job. And it’s not in your budget.

So let’s talk about the ants first. The easiest way to deal with the ants is to use ant baits all along the perimeter of the building (outside and inside), or at least where they are coming in. They generally come in the house looking for food. So make sure there is nothing for them to eat in side the house. Seal up with an exterior calking any gaps on the outside first.

Then work on the inside at the perimeter of the floor. Use a flat prybar and remove any quarter round moulding that is at the bottom of the baseboards. Fill any gaps here that are between the baseboard and the floor, then replace the quarter round moulding.

And lastly and most difficult would be to work from beneath the floor. Clean the area between the joists with a vacuum and brush out any dust that is in the visible gaps between the floor boards. Use an flexible acrylic calking on the outermost floor board gaps. You needn’t do more than just the perimeter areas, as doing the whole floor would be daunting.

Oh, and if you have a finished ceiling in the basement or it’s really awkward to work under the floor, you will have to seal the gaps from above. But try this. Take some thin cotton rope and stain it darkly with a wood stain that will be darker than the color of the floor. Choose a size of rope that is about the right size for the gaps, several sizes may be needed. Lay a thin bead of clear non silicone flexible calking in the gap, and then force the rope in the gap. Let this dry for several days, and if you wish apply a coat of varnish to just the top of the stained rope. It’s best to keep the rope quite thin so that the gap isn’t entirely filled but slightly concave. Flexible calk is used so the boards are not glued together, and will move seasonally. Again you should only have to do this out a few feet from the wall, I hope.

As far as the ants, make sure they are not CARPENTER ANTS which feed on damp or decayed wood. You will see little piles of wood bits as they eat the decayed wood. You WILL have to call an exterminator for these little beasts, and repair the wood. Ants in general will follow a scent trail followed by their buddies who have found the food inside the house. Clean up the food, but also clean up the trail with disinfectant to fool the followers.