How to Square Diagonal Hardwood Floor Installation


Old 09-16-19, 11:29 AM
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How to Square Diagonal Hardwood Floor Installation

Hey guys,

I'm installing some 3/4" hardwood flooring in my LR/DR, and I want to lay it diagonally... (Yes I have the extra for waste etc)... The problem is that everything I look at says to start from the middle of the room to keep it straight, and I really can't do that because the room expanse is a weird shape (L). I've read that many people have success starting at the corner, as long as you move shims along the edges so they don't bow back toward the wall when you nail it down.

Regardless, is there an easy way to square the room when starting from the corner? The 345 thing shows my starting corner is NOT square, and I'm not sure how to approach it to MAKE it square to start. With the flooring being 45 degree, I don't want to have to keep staggering the edge the entire way if I'm a little off. I'd like the expansion gap to be as uniform as possible...

What would be amazing would be a laser square for INSIDE corners instead of OUTSIDE corners, so I could stick it in the corner and shoot myself a perfect line about 1/2" away from the intersecting walls, and just adjust by sight so it'd look good when complete. Instead I have an outside corner one (tile laser) where the laser won't hug the wall, but instead squares about 6" out from the walls if I flip it around. This creates a situation where I'd have to measure back 6" along the entire line and won't be as accurate.

Even doing the chalk line thing along the walls is hit or miss, as I've tried a few times and just cant get a perfect square.

How the h*ll do people quickly do this? What am I missing here?

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Old 09-17-19, 01:15 PM
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Anybody? Easy way to square a corner or lay a grid in a weird shaped room?
Old 09-17-19, 02:00 PM
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FYI: I am not a pro and have never done it but perhaps a couple thoughts I will help.

I am not sure why you are worried about square when you are installing it diagonally.
As long as you start in a corner so that when you hit the inside corner of the L the nailing side (tongue) is still open.
If the sketch I made for myself is correct. The upper right inside corner and the upper right side of the bottom would be a bad places to start because when you get to the inside corner of the L in the room the tongue ends up on the wrong side. I hope this makes sense!!

I would just measure out from the start corner and mark each foot, then snap a chalk line so that you can tell if you start going off your 45 angle.

The first start piece and a next couple pieces will be a pain trying to nail so I would (predrill if a solid hardwood) and then nail them by hand once you get a solid (non-movable) base set then switch to the nailer.
Old 09-17-19, 02:13 PM
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I did my LR/Dining room floors on the diagonal. I didn't overthink it, not because I knew what I was doing but because I didn't know any better, I just started in a corner, cut the ends of the boards at a 45 and started laying them out. As long as the walls aren't so out of square that any angle error can't be covered by baseboard you'll be OK. I did frame the areas around the fireplace hearth and then measured and cut each individual board for a tight fit with the framing.

I think you will be glad that you did the angled install. When I had mine refinished a couple of years ago the guys that did the job were very complimentary and they complained how most builders are too cheap nowadays to do anything but a straight layout.

I would post a picture but my floors are no more. Ripped out after the fire and I'm probably gonna' get a hassle from my insurance guy when I tell him that I want a diagonal replacement.
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Old 09-17-19, 02:35 PM
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If it's L shaped, I would snap a reference line parallel to your longest wall, splitting the difference as you measure to the walls on either side, so that you aren't creating a giant taper on one wall or the other.

Then, using that line as one side of your right triangle, do 3:4:5 off that line, and make a diagonal chalk line that goes right past your outside corner.

Start your first board on that diagonal chalk line, and put a spline in it, and nail it down on both sides... then you can work outward in both directions from it.
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Old 09-17-19, 05:42 PM
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Opposite walls are seldom parallel so you will have to custom cut each piece for the row ends so why not just snap a line from inside corner to outside corner of the L and go from there. I am assuming there are 6 walls involved here with 2 corners ending up with very short pieces. These 2 corners should not be heavy traffic areas
Old 09-22-19, 03:30 PM
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@cwbuff - What did you mean about the hearth framing? You mean you framed around it with the flooring and then ran the diagonal up to that? Or you used some kind of shoe?... I've got the same situation and I haven't decided what to do with it yet. The floor is going to butt right up to the hearth and I don't want a big gap there that isn't covered~

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