Hardwood and Building Code

Factual Questions
1

We are replacing carpet with hardwood. In the corridor the current hardwood is perpendicular to the hall. We wanted the same pattern where the two meet but the floor guy insists that according to code the wood must be laid parallel to the support joists and so we will have wood coursing in two directions. Actually when we came home he had already laid it in that direction. Could this actually be true, or did he screw up and then make up a lie?

We live in Maryland. When I searched online I could only find code concerning the subfloor. Nothing about the actual hardwood above it.

2

I’ve never heard of that. I’m assuming you have a subfloor? Plywood? You can call your local building inspector’s office and ask.

3

Many manufactured flooring is not strong enough on its own to span longer distances. So it needs to be laid sideways across the 16" or 24" spacing of floor joists, or to have a plywood subfloor installed that it is laid on top of.

But I don’t know if that is ‘code’ anywhere – most areas just rely on the common sense of the installers to make sure that it’s done safely.

I’d just put a transom trim board where they meet, with an appropriate contrasting color or pattern.

4

This will vary by location - Renee nailed it in first post.

But: if you have floor joists on the first story, you are not on a slab, which suggests a pre-WWII construction.

Before the advent of plywood, they used 1x10’s as sub-floor material.

I cannot imagine any construction in which the floor covering serves as a structural function.

IOW: the guy screwed up and is trying to bullshit his way out of it.

I’d find another floor guy.

5

You wouldn’t want the hardwood to run parallel to the joists. you would want it to run perpendicular to the joists. With a normal subfloor it can run any direction whatsoever.

6

@t-bonham: Given that the OP is pulling up existing carpeting to lay the hardwood, it’s a very, very good bet there’s a subfloor of plywood, OSB, etc.

My bet is the installer doesn’t know why flooring is normally laid across the joists, he just knows it’s (commonly) done that way. So he’s assuming it must be done that way.

As said by others above while I was typing, time for more investigation and a new floor guy.

Or any house with a basement.

7

Yes, there is definitely a subfloor.

8

The original part of my house was built in the 1890s, and there is no sub-floor. The hardwood flooring is laid directly on top of the floor joists. This is in CA.

9

Or a crawl space. There are lots of good reasons not to build on a slab.

10

In post-and-beam floor framing, the beams are four foot apart and covered with 2x subfloor material perpendicular to the beams … over these 2x’s is 1/2 inch underlayment (either plywood or particle board) … that’s all the structural form needed … thus the direction of the hardwood flooring doesn’t matter …

The guy working on your project is yanking your chain …

11

They’re more commonly called girders, and there isn’t usually an underlayment over the 2x material. At least not here in CA. In the 60s, if they didn’t build on slab, it’s usually 2x6s as a subfloor laid diagonally. Then hardwood on top of that. These days, it’s typically 4x6 girders, 2x6 floor joists, then 3/4" T&G plywood subfloor (for the 1st floor).

12

I’ve occasionally worked a girder-and-joist floor … 4x6 12’ o/c and 2x10 32" o/c with an 1-1/8" plywood subfloor … and once we poured a kneewall instead of using the 4x6’s … but here locally we see many more post-and-beam … saves money because we can use the concrete forms as subfloor … underlayment here is cosmetic and doesn’t serve any structural purpose … a 2x subfloor tends to be a little rough so tossing down a layer of 1/2" particle board gives the floor a nice smooth finish … maybe CA doesn’t require a vapor barrier either but here we have to put a layer of light tar paper between the subfloor and the living environment … underlayment doubles down on this plus protects the vapor barrier … Western Oregon … moisture is the enemy …

Either way … the flooring can be run in any direction … it doesn’t need to provide any shear since the concrete stem wall doesn’t rack … even during earthquakes …

13

If the hardwood is a replacement for carpet, and all you are doing is pulling up the carpet - well, carpet has no structural value, so whatever and however you replace it with is equally irrelevant. particularly, modern hardwood is tongue and groove and AFAIK not nailed down through the subfloor to the joists anyway - so even laid across the joists, it would not be significant stronger structurally. Plus they are random shorter lengths, so it’s not unusual there would be unsupported butt ends between two joists. I assume any requirement goes back to 1800’s architecture, when floorboards were the “subfloor”, had nail-holes on top, were nailed into the joists, and structurally that’s what kept you from falling through.

14

Likewise for my mom’s house in Ohio, built in the 19-teens. If you go down to the basement, the ceiling is the same boards that make up the floor of the first story, and there are occasional gaps large enough to let light through.

15

I pressed them on the direction thing. They say if the lay it across the support then it is less likely to buckle. Given it is over a subfloor it seems the oak would have no idea which direction it is related to girders. Does this explanation sound reasonable to you?

16

The best way to prevent buckling is to keep out moisture. Since you’re putting this on plywood, I can’t imagine it would matter.

17

Is the existing hardwood perpendicular to the joists? If it is, and you have had no buckling problems, then I don’t see any reason why the new hardwood would buckle if laid perpendicular to the joists.

I did a quick google and according to This Old House it is standard to run the hardwood perpendicular to the joists and you can only run parallel if you have sufficient subfloor: Running with the Joists. It also says that running the hardwood parallel to the joists may void the floor’s warranty. :eek:

18

I believe flooring is almost always perpendicular to the joists. Older houses did not have a subfloor, hardwood floors served a structural purpose, so they always had to be perpendicular to joists. I am pretty sure there would be less buckling if flooring is perpendicular, reason being the floor boards wouldn’t be running with the hills and valleys of the subfloor settling on the joists. Putting the flooring perpendicular to the joists increases the stability of the subfloor.

I know exactly why the contractor is saying that: He didn’t want to cut the boards to the width of the hallway. If he ran it length-wise he would get the job done faster and have less waste.

From my experience in the construction field (and having worked at Lowe’s) most flooring contractors are on the low-end of the totem pole when it comes to skill level in comparison to other trades. A lot of times they are the guys who can’t cut or paint a straight line, can’t complete an apprenticeship, etc. They can be pretty rude sometimes too. So any flooring contractor needs to earn my trust.