Installing Glue Down Hardwood Floors - Page Four

What kind of tools do we need for a glue down installation? Besides your basic power tools, proper trowel notch size is critical in bonding the hardwood to the concrete. Another common reason for installation failures is the wrong notch size or the installer was too lazy to buy the right one. All adhesive manufacturers provide a detailed description of what type is needed. They will vary from parquet installations, engineered, and solid. In this case we'll be using a trowel notch size that will cover approximately 45 square feet per gallon.

Adhesives Can Be Very Messy!

Think ahead. The most common adhesives used for gluing engineered hardwoods are urethane based with Bostiks being the leading producer. It's some real messy stuff if you're not careful. At all times keep an eye on where you are during the installation. Always place containers being used on a piece of cardboard or the like. It loves to ooze all over the place for lack of a better description. The same is true of the trowel.

For professionals that never used this type of adhesive it's always a learning experience. I'll admit, my first experience with Bostiks wasn't a pretty one as I had the stuff all over me. By keeping the adhesive in check, less will be tracked onto carpet or areas already installed. Any smudges, drips, and oozes should be cleaned immediately with mineral spirits and a rag. Yes, mineral spirits are safe with prefinished hardwood floors, but not ones with waxed finishes. If in doubt test first.

Lock Away Those Critters. Kids Too

Pets and small children are not the place for this type of work. The worst thing you want to deal with is having a critter stuck in the middle of the adhesive. Plan ahead and keep them out of the way. Kids can become extra curious, it's something new. Calmly warn them they should stay away or they may get glued to the floor.

Getting That Starting Line Snapped

As mentioned on our layout and squaring up page, few rooms will be square. It's a wise idea to check how far out of square it may be before you start. Using a tape measure get a measurement from two opposite wall lines and compare the two numbers. Depending on the width of the material, our starting area should be 30-36" from the baseboard or drywall. In our example we're using a 3 1/4" width engineered product. We've multiplied 11 x 3.25 and added 3/8" for our expansion space that will be covered with shoe molding after the floor is laid.

Expansion isn't as critical with glued engineered products as it is with floating floors or nail downs, but you will need some area to get those last few rows into place.

Not all products are created equal. We suggest placing ten boards together checking for size. Where it may be 3" in width, ten boards may not equal 30" This is common with lower quality products as the milling is not as refined. It may be a good idea to add another 1/4" on top of our example of 36 1/8" Otherwise you may find yourself having to cut a smidgeon off with the last board to fit the parallel wall area.

Having marked two areas from our baseboard on each side of the working area, snap a chalk line. This will become our starting line. In this case our helper was nowhere to be found so a full bucket of Bostiks did the trick. Once we have our starting line, double check how it looks on the opposite wall with the tape measure. It's also a good idea to check against the starter wall area as some walls or baseboard may not be straight.

Oh, did we mention sweeping the areas first? Another contributing factor in glue down failures includes dust and dirt. For best results we recommend sweeping and vacuuming the areas prior to anything. Keep your working area clean and organized. Hardwood flooring will ding and scratch. I can't count the number of times I've walked in on some professional installations and seen tools scattered all over the place. All it takes is one careless person walking over the tools and you have dings in your brand new floor.

Getting That First Area Laid

The starting area is the most important in any installation. If we're looking at a single room, the biggest concern is how square you are in that area. However, if the installation goes into other areas and your starting line is out of square to these areas you'll find yourself correcting as you go along. This is why we recommend a control line.

A control line is the reference point for the entire layout and should be utilized near the center. In this case find the longest parallel wall, measure out, and set a chalk line halfway across the room or nearer to the center of the entire installation. From here we recommend making reference points in other areas checking to see how square we may be from our control line. In other words, measure away from the control line and get another chalk line set. Check measurements against all parallel wall lines and make necessary adjustments. For more technology inclined, lasers can also be used for squaring up, but actual control lines should be visible at all times.

Back to the starting area. Measuring out 36 1/8" from our base we've snapped our starter line. Once the adhesive is spread we're ready to work off that line and towards the baseboard. 36 1/8" in this example equals 11 boards at 3 1/4" each--plus 3/8" for the base or molding to cover.

Place your first row directly on the chalk line, proceeding to add a few more rows staggered as much as possible as shown in the image to the right. Once you have a few rows started use some scrap pieces to be used as backer boards to keep the installation from moving around in the adhesive. Attach them with concrete cuts nails, preferably smaller ones or 3 1/2 penny. Some have noted hot gluing scraps to concrete may also work and be less troublesome. A very clean surface is important for this to work.

Working from left to right continue to fill in the area where the adhesive had been applied. Don't forget about that can of mineral spirits and a rag. Your first experience with this adhesive will not be a treat and it's important to cleanup as you go.

Depending on how well you've spread the adhesive you may get some ooze over the starting line. When spreading try to keep the adhesive 1/4" away from the line. If you should happen to stop for a day or two, make sure the area and the groove is clean of any excessive glue. Trying to engage the next row with a dried glue clog can be a frustrating experience. Always check before spreading any additional adhesive or when finishing for the day. Otherwise you will not get a tight fit of the old area to the new and gapping will be inevitable.

If we've measured correctly, our last row should fit in nicely with about 3/8" left. Depending on the product quality it may be tight. Place the last full piece while utilizing a pry bar against the base or wall (use cardboard or putty knife to protect from dinging) to pull the installation tight. Insert wedges into the area to keep the tight fit as shown below. At this point your starting area should be tight as a drum and should not slide out of place. However, I would keep a close eye on end joints for a few hours as they have a tendency to open up at will.

Other methods used for keeping floors tight include blue painters tape, but should be removed once the adhesive sets. Follow individual manufacturer directions as some do not recommend this procedure because it can affect the floor finish. Wedges can be made from scrap pieces on the power miter saw you are using.

Cleanup As You Go!

Once you've completed the starting area, go over it thoroughly with a rag and mineral spirits. There's nothing more frustrating then having to clean cured urethane adhesive once the job is complete. In this particular job, and my attention to cleaning as I go, I still spent two hours on 1200 square feet cleaning spots that I missed or glue that got tracked from one ooze to another.

Continuing The Installation

Once our starting area is complete, remove our starter boards very carefully and measure out another area to be worked. Use whatever measurement you find more comfortable. 24, 30, or 36"(based on 3" width) away from the original starter line. Get another chalk line going and spread the adhesive again.

Knee Pads and Other Stuff