wood resting on metal & concrete

This is standard house construction in most of the US, wood frames on a concrete footing or foundation. As long as the wood and the concrete or metal is not going to be wet and you adhere to any code restrictions on distance between wood and soil there should be no problem. If it's going to be wet or close enough to the ground for termites etc to build a bridge into it then you want treated lumber or a decay resistant species same as you would for deck construction.

Reply to
J. Clarke
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Eventually I'm going to build a simple staircase out one of my back windows into my yard ­ currently I have to go to the basement to get to the yard.

The staircase will rest on metal and concrete, which is a bad thing, no?

Wondering if there's any techniques people use to space wood from concrete/metal? I'm imagining tough plastic or wood "dowels" that would work as spacers, or strips of rubber or plastic.

Any ideas appreciated.

-Ben

Reply to
Ben Gold

Can you use pressure treated stringers? Mine has been on concrete for over

15 years with no noticeable deterioration.
Reply to
Edwin Pawlowski

I put everything like that on strips of heavy tarpaper, sometimes two or three layers thick as long as a little settling from compression isn't a problem. I've used untreated lumber on concrete for years like this with no problems. I do however live in an area fairly dry.

Reply to
CarlGoodall

I used heavy stainless lag bolts (4 inch length) screwed into the stair frame (stringer), where it meets the concrete. The pointee part of the lag bolt points skyward, the head side rests on the concrete slab. I used two lag bolts on each stringer. I left the bolts protruding about 1 inch. The heads of the lag bolts sit on the concrete slab. After assembling the stairs and bolting them to my patio, I adjusted the hex head lag bolts using an open end wrench, to compensate for any irregularities in the concrete slab. This prevents the stairs from "rocking" because one or the other stringer isn't sitting exactly on the slab.

The advantages to me are. 1. As / if, the slab settles, I can adjust the bolts to compensate for the new "gap".

  1. I have air flow under the wood stair support (stringer) so that any water will dry up faster.
  2. The stainless lag bolts won't be a problem in my future.

In my part of the world, rain is a very big part of life. I feel that anything that holds water, such as the joint between anything exposed to water, is a problem in the making.

Ben Gold wrote:

Reply to
Nirodac

The best material to use is a layer of elastomeric roofing membrane, more commonly known as ice and water barrier. Its use extends not only to roofs, where it is used one everything from flashing to chimneys, but also to carpentry and framing, where it is used around windows and under mudsills for the same reason as your stairs. This material is a fairly thick rubbery membrane, imperivous to water, with an extremely sticky coating on one side. Once you stick it down, it is nearly impossible to reposition. You should lay the membrane down in a strip where the stringers will fall.

Reply to
woodworker88

I agree, it is great stuff. Better than tar paper in every way. I did a small low slope roof with it and plan to use the rest under the wood on my deck that will be resting on concrete.

Reply to
CarlGoodall

Untreated wood should be a minimum of 6" from soil & 1" from concrete to avoid rot & termite problems.

Wood in contact w/ concrete should be treated or decay resistant species. The key to making wood last is to keep it dry.

Please don't anyone quote the code to me;

the code is a minimum standard, a compromise at best, like using a brain surgeon who got all C's. :)

cheers Bob

cheers Bob

Reply to
BobK207

Right, but my question was does anyone have a technique to keeping wood dry?

Like say I made a wood table for my patio. Instead of dealing with pressure-treated wood and solutions like that, I was thinking of having some sort of rubber/plastic footings (say 1" high) to keep the wood off the concrete.

My question is what do people do when the build wood that is going to sit on concrete to remedy the problem? Any specific materials or techniques?

Reply to
Ben Gold

Stop. You're focussing on the wrong problem. FORGET THE CONCRETE. CONCRETE IS NOT YOUR PROBLEM. Your problem is keeping the wood dry.

Are these stairs going to be in a stairwell with walls and a roof and siding and a door and so on like any other part of the house? If so, then you build them just like any other part of the house--examine the house to see how it was done or obtain a book on residential construction. Generally speaking for that kind of construction the codes require a footing or foundation that extends 3 feet or so above the soil and a decay-resistant sill plate on top of that, with the outside steps either concrete or decay-resistant. My house was built before pressure-treated sills were required and it's been here a long time without any problems related to the sills and concrete. A friend's house has similar construction only the foundation is mortared stone rather than poured concrete--it has been there longer than the United States and is quite sound. And they didn't even _have_ treated lumber then.

If the stairs are going to be outdoors without a roof then your problem is not concrete, your problem is that they are going to be outdoors. You need to build them accordingly. That means decay resistant lumber. Forget the concrete--they're going to get wet top to bottom and have plenty of nooks and crannies which are going to hold water long after the rain stops. If you don't do that then one day you are going to put your foot through a step. No ifs, ands, or buts. Just when.

To take your example of a wood table for your patio, what people do is use treated wood, decay resistant wood, or toss it when it rots.

I don't know where you get the idea that using pressure treated or decay resistant wood requires any kind of special "dealing". You buy it, you mark it, you saw it, you assemble it, you finish it. Decay resistant doesn't change any of that.

If you're looking to do this on the cheap, then don't do it. If you've never done this sort of thing before and your budget is so tight that decay resistant wood is going to break the bank, then trust me, you're going to run out money halfway through.

Reply to
J. Clarke

I didn't catch the beginning of this thread, but does the design you have in mind *mandate* that the wood has to be sitting right on the concrete? Even raising the wood a few inches could make all the difference. As I'm sure you know, a metal stand-off is usually set in newly poured concrete for the mounting of wooden posts. Assuming that the concrete you're mounting on has long been set, what's to stop you from using a hammer drill to drill a new hole and setting in a new metal stand-off?

Reply to
Upscale

On the last building I put up, we used a foam product that came in rolls 6" wide. Laid it on the slab, and just puched the lag bolts through it. Then we put on a pressure-treated sill plate, bolted it down, and nailed the framed walls onto the plate. It wasn't strictly necessary for code compliance, but it seemed like a fine idea.

FWIW, I've put in several sets of deck stairs that were just regular treated lumber screwed to treated 4 x 4's that were set directly into concrete footings, and they've all lasted for many years. As long as you take care of the steps (put a sealer on them every year or two), they should be fine.

Aut inveniam viam aut faciam

Reply to
Prometheus

Shape the concrete so that it does not form a pool, provide hight points for the wood to rest on, think where the water will go when (not "if", it *will* get in) it gets in and provide drainage.

Reply to
Juergen Hannappel

thanks all for the various ideas, gave me many options!

-Ben

Reply to
Ben Gold

Every outdoor wood I've seen corroded first wherever it rested or was attached to concrete. Yes, I'm new to building outdoor things, so calm down. I understand that I should build with water-resistant wood. Maybe I'm overly afraid of the water/concrete thing. Thanks for all your helpful info.

Please don't make assumptions that lack of experience in building makes me cheap or poor (not poor! oh no!). I don't like pressure-treated wood. I didn't say I wouldn't use the appropriate wood, just not pressure treated. Or I'd like avoid it for a table or furniture at least.

-Ben

Reply to
Ben Gold

A lot of good sound advice here. Just one suggestion: Should you not treat cut ends? Any treatment I've seen doesn't go through and through.

Reply to
Guess who

Well it's most colored and ugly green or brown, warps like crazy, species usually unknown and toxicity still a question mark.. If you like that in a wood use it.:) I'm betting you have a whole yard full of those attractive 'landscape ties'. I'd rather have a car up on blocks in my front yard than those hideous and possibly toxic landscape ties.

Reply to
Jimmy

Well, that's assuming a lot from what he said. "Decay-resistant" doesn't always mean "treated", and "treated" does not mean "railroad ties" If the plate is going to be covered up, then it makes all the sense in the world to use treated lumber- if it's going to be an essential part of the project's design, then there are several species to choose from (cedar, teak, redwood, mahogany, etc) that will do just as well (often better) than the pressure-treated stuff you can get from the Borg. And even the pressure-treated stuff is a whole lot nicer than you're making it out to be. The worst stuff I've seen has a slightly green tinge to it, but otherwise looks just like any other framing stud on the stack. Aut inveniam viam aut faciam

Reply to
Prometheus

I'm sensing some hostility here. Why is that?

Just for the record the only "landscape ties" I've ever owned were sitting behind my father's garage in a pile and they were creosote-treated ex Coast Line.

There's nothing about pressure treatment that makes wood that won't already "warp like crazy" warp like crazy, most of it in the US is Southern Yellow Pine, used because it takes well to the treatment, and toxicity is well established for most of the treatments.

But "decay resistant" does not require pressure treatment. That's why I stated "or decay resistant". There are many species of wood that are naturally decay resistant--how resistant you need depends on where you are. I believe I already suggested that you check woodpicker . Setting "decay resistance" to "high" gets more than 40 species and they don't have ipe in their database yet. Colors range from nearly white to purple to red to brown to black--don't think there's a green one in there.

Within that "high" range there's variation--osage orange is going to last longer than white oak for example, and if you're in zone 4 or 5 on the map at I'd do some further research before selecting wood that was going to be resting on footings or in ground contact.

Since you're concerned about your lumber "warping like crazy", adding "stability--high" to the list narrows it down to 35. So what other properties do you want?

Reply to
J. Clarke

Sorry, I live in a neighborhood surrounded by hundreds of landscape ties. I hate those rounds ugly sticks.:)

Reply to
Jimmy

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