# What's the best method to chalk a line parallel to a wall?

I have read some great listings on setting a chalk line but remain with a question ... if you are trying to get the line to run perfectly parallel to a wall, it is for hardwood flooring, so that the line will be parallel to a wall that may not itself be at a right angle, and/or uneven, how do you do this? If I use the wall to measure out, say a half inch, and the wall is not straight, by the time I get to the other side of the room I may end up with boards that are all not perfectly parallel to the wall.

Help!

• Technically this is not an answer, because I am proposing a different solution: run your boards at roughly a 45 degree angle to the wall. By using a deliberate offset like that, it will be more difficult to see anomalies caused by non-square corners or non-parallel walls (which are common as a house settles). Plus, it looks fancy. The same approach works with linoleum that has squares or lines on it.
– user4302
Dec 2, 2015 at 19:10

"Parallel to a wall" is a subjective thing. Parallel to what? Parallel to a line crossing the corner points? Parallel to an average wall line?

Generally, a carpenter takes one of two approaches: Either measure out from each corner, taking into consideration anomalies such as rounded plaster or drywall, and use that. Or, if there's a nearby perpendicular wall that's considered more trustworthy, use the 3-4-5 technique to strike a right angle from that, or from a line snapped parallel to it.

The key to any such process is getting as wide a sample as possible. Minimize extrapolation (extending your chalk line beyond measured or calculated points) and use as much length as you have available to make your line marks.

In the case of your flooring, it may be more important from an aesthetic perspective to achieve the illusion of parallelism, and not true parallelism. Consider your entire scenario and find the best compromise. Chances are that you'll have to rip the edge plank to fit a wavy or crooked wall regardless, depending on the thickness of your base trim, etc.

Be sure to measure across the room and determine how parallel you'll be with the opposite wall. If your flooring will extend into other rooms, examine those as well.

• Or, if they're trying to fit something precisely to a less-than-perfect surface, they'll scribe it to shape, using that surface directly as a template. Remember, in any house more than a few years old, phrases like "straight", "parallel" and "square" are often more theoretical than real, and the trick is knowing how to deal with the variations in a way that isn't glaringly obvious. Dec 2, 2015 at 16:00
• Good point. That's likely necessary with any approach and even in newer homes. I implied as much at the end of my third paragraph. Dec 2, 2015 at 16:05
• The other trick is to make sure there's at least a half-board on each side of the room and bury the edge under shoe molding. Dec 2, 2015 at 16:14

I think what you are trying to ask in a roundabout way is how do you get the hardwood flooring runs to lie in place so that nobody can sense there are any out of parallel walls. if this is the goal, the wider your boards, the less you will see non parallel walls. after that its a little bit of an art form. however, try this:

1) assuming you are using prefinished flooring, running the long joints down the long axis of the room, and that the room is rectangular. measure and mark the center of the room on the long axis. chalk a line from these two points.

2) take measurements to the long walls along their lengths to see how far the walls deflect over their runs. usually one wall is out somewhere. you should see a taper over the room, but you might get lucky and have perfect parallelism. if one wall is tapered, you will have to decide which one to use as the start wall. the outside wall is usually the one with all the furniture pile up against it, so it can hide much of the visibility of a tapered floorboard/baseboard interface, so you could start with the other wall.

3) measure your rooms width and divide by the actual board width. if you get a perfect number, then you are good to go. if not, that means the last board run will need to be ripped. you will have to take careful measurements and figure out approximately by how much before you lay any wood. you don't want to end up with a 1" wide board as the last board run, because if you have to taper it, your eye will notice the taper much more than if you have a 4" board as the last width. you are best to split the difference, so that you have to rip the first course and the last course (easier for fitting under doorframes, etc)

4) when you start your course of hardwood, leave more of a gap at one end of the first run to compensate for the taper. but don't do to much. the human eye can pick up approximately 1/2" in 8 ft in my experience.

5) lay your floor. its now going to be the best in can be for a given space that has non parallel and/or undulating walls

Rooms are rarely, if ever, square. The trick is to find the area(s) where non-parallel lines will be most noticeable, and make sure that these look good.

Generally this is where the new floor will run next to other parallel lines on (or near) the floor. Examples would be:

• Room transitions from the new hardwood to tile (or other flooring with grids)
• Around a brick or tile fireplace hearth
• Around a large air register

It is important to square everything up around these features and make sure all the long parallel lines are true to each other.

Another technique, if you can't square up everything, is to butt the ends of the hardwood planks against a problem area. It will be much less noticeable. An example might be a "wavy" wall.

I think you are trying to say you want a straight line to start your flooring from. Whatever width your flooring is, I usually measure out from each corner 1 inch more. You will then have to fasten a row of flooring with the edge that will be away from the wall on that line. then measure from the edge towards the wall to the wall and find the spot with the greatest measurement. Use a block of wood and a pencil, or a pair of dividers with a pencil, (compass), set about 1/8 of an inch more than your measurement. holding the block, or one leg of the dividers against the wall, start at one end and slide it along the wall making a mark on the flooring with the pencil. Cut off the edge of the flooring on the side of the line toward the wall "scribing" it to fit the wall. I even put about a 5 degree bevel on it so only the top touches the wall. If you are using tongue and groove flooring the groove edge is always against the wall you are starting from. If you do not think the room is close to parallel start from he wall people will see first when entering the room, or the longest wall.