2nd floor in garage

Question Icon
Posted by: from Hamilton
8/17/2012 at 4:38:18 PM

Do I use 2x4s or 2x6's for the 2nd floor of my garage?

The garage is 25ft x 25 ft and the 2nd floor will carry a medium load. I'm just not sure what code is.

User Icon
Date/Time8/17/2012 at 5:49:24 PM

Hi Barb,

Always go with the stronger ones. The stronger the better. You say, the 2nd floor will carry a medium load. What is if you change this later for whatsoever reason or you sell the house and the next owner put more weight on the floor?


3D-Tile-Design - Bertram Tasch

Maple Ridge, BC (Greater Vancouver)

-1 (778) 886-9503

User Icon
D.S. Renovation, Construction and Design in Toronto
Date/Time8/17/2012 at 5:58:14 PM

Whenever your building any structure like a garage or extending up or out. You should use 2x6.

User Icon
Date/Time8/17/2012 at 7:48:10 PM

Hi Barb

If you are talking about the floor structure you can't use either, along with an engenered center support beam, the floor joist would need to be 2x12's with 16 inch on center. Your dealing with a 25ft. span.

If your talking about the walls, you could go with 2x4's, but I would suggest 2x6's if only for the insulation factor.

Good luck

User Icon
Acme Contracting in Whitby
Date/Time8/17/2012 at 8:15:55 PM

Hi Barb,

I'd go with 2x8 personally for floor joist, with 16" centre.

User Icon
SVS General Contracting in Conklin
Date/Time8/17/2012 at 10:14:47 PM

Building code requires you to go with 2x12 with 16 in. centers. The other thing you have to be sure of is that the main structure you are building on to or up to can take the added load that will be put on the walls. It is smart to get an engineer to check it out the cost will be worth it in the long run as you could be told to redoe it if the joists are wrong to start with.

User Icon
Spencer from All Home Repair in St Thomas
Date/Time8/19/2012 at 9:55:46 AM

I'm not sure what you mean by 2nd floor. Will it be a usable space or living space? If not, does any of the roof load come down to the floor joists. Either of these situations add to the load on the floor. The type and grade of lumber also makes a difference in load bearing strength of the joists.

If you have any of the additional loads as above then you need to factor in about 60 lb per square ft of load area, ie the size of your garage. Then find out the load bearing rating per foot of the lumber used.

The is a bit of research involved and even then you will be responsible for the resulting structure. A qualified contractor or even better an engineer would take on that responsibility.

Good luck


User Icon
Date/Time8/20/2012 at 11:13:35 AM

Hi Barb:

Firstly, I would imagine that in Hamilton, you will require a building permit for the structure. They will tell you what you have to use as minimum and the support that you will require. Always build for future needs and usage, for as mentioned, when you sell, the next party might have a different use for the area, and require a heavier load bearing issue. I once built a 14 by 16 elevated deck for a "possible" future hot tub placement. Not only did we have to think in terms of the weight of the deck with 6 to 8 people, but had to include the 10 person hot tub filled with water, 10 people in it, 10 people additional on the deck, and 3 feet of wet snow (Vancouver Island).

If the space is going to be used for normal living think outside the norm and consider an engineered truss system. These are essentially a wooden I beam and can be ordered for different loads. I have a 25 foot span in my basement and I didn't want posts, so I have an 11 7/8 TJI with no centre suport. Depending on the code in your area, this might be acceptable. The firm that supplies them calculates the load, the span, and the load carrying capacity. They come in a variety of load ranges. Mine happen to be a series 300 TJI, which are 11 7/8 on 16 inch centres. In addition to the increased strength, they give a wider base for your plywood subfloor to be screwed and glued to. I use 3/4 subfloors which are over code in B.C., but give a firmer floor for the finish flooring to be placed upon.

Above all, use a reputable contractor with good references.

Enjoy your new room.


User Icon
McInnis Contracting in Belleville
Date/Time8/21/2012 at 12:51:11 PM

The main walls in the garage need to be 2x6 first, then depending on the truss style for the upper walls.

User Icon
McInnis Contracting in Belleville
Date/Time8/22/2012 at 10:09:05 AM

Well as mentioned, the main walls in garage need to be 2by6 first. Then depending on truss style for upper walls.

Search the TrustedPros directory and discover the best contractors in your area.

Find your home service pro
Great renovations start with a great contractor.

Since 2004, TrustedPros has been helping homeowners find the right contractor for their home improvements and repairs.

Post Your Project

Within hours you'll be comparing offers from top-rated professionals. It's free to post and you're under no obligation to hire.

Trustedpros Inc. does not warrant the accuracy, completeness, safety, legality or usefulness of any Content, or Whether Content is Current and up-to-date, and TrustedPros Inc. Shall have no liability whatsoever with respect to your use or reliance upon any content or for content being removed or otherwise ceasing to be available. Please refer to the terms and conditions of use of this websites for more details.

Get quotes from top-rated contractors