Thread: Soil distance from masonry veneer and wood siding

For years (literally) I've had it in my head that the soil level should be 4 inches below the brick on a slab-on-grade home and if there is wood siding the soil should be 6 inches.

As I am want to do, today my brain said, "why do think/believe this to be true?". So I pulled out my code book (well actually it's software on my computer) and my handy Code Check.

I have found this rule: (from IRC 2009)

R404.1.6 Height above finished grade.
Concrete and masonry foundation walls shall extend above the finished grade adjacent to the foundation at all points a minimum of 4 inches (102 mm) where masonry veneer is used and a minimum of 6 inches (152 mm) elsewhere.

My Code Check actually states it this way: Masonry veneer ledge 4in above earth, wood sill 6in min.

This isn't saying that siding needs to be 6 inches from the dirt. Did I pull this out of my back side? Is it Alzheimers? Does anyone have an answer?

Thanks in advance. Bruce

Originally Posted by JB Thompson

My Code Check actually states it this way: Masonry veneer ledge 4in above earth, wood sill 6in min.

This isn't saying that siding needs to be 6 inches from the dirt. Did I pull this out of my back side? Is it Alzheimers? Does anyone have an answer?

Thanks in advance. Bruce

From the 2009 IRC:
- SECTION R317 PROTECTION OF WOOD AND WOOD BASED PRODUCTS AGAINST DECAY - - R317.1 Location required. Protection of wood and wood based products from decay shall be provided in the following locations by the use of naturally durable wood or wood that is preservative-treated in accordance with AWPA U1 for the species, product, preservative and end use. Preservatives shall be listed in Section 4 of AWPA U1.
- - - 1. Wood joists or the bottom of a wood structural floor when closer than 18 inches (457 mm) or wood girders when closer than 12 inches (305 mm) to the exposed ground in crawl spaces or unexcavated area located within the periphery of the building foundation.
- - - 2. All wood framing members that rest on concrete or masonry exterior foundation walls and are less than 8 inches (203 mm) from the exposed ground.
- - - 3. Sills and sleepers on a concrete or masonry slab that is in direct contact with the ground unless separated from such slab by an impervious moisture barrier.
- - - 4. The ends of wood girders entering exterior masonry or concrete walls having clearances of less than 1/2 inch (12.7 mm) on tops, sides and ends.
- - - 5. Wood siding, sheathing and wall framing on the exterior of a building having a clearance of less than 6 inches (152 mm) from the ground or less than 2 inches (51 mm) measured vertically from concrete steps, porch slabs, patio slabs, and similar horizontal surfaces exposed to the weather.
- - - 6. Wood structural members supporting moisture-permeable floors or roofs that are exposed to the weather, such as concrete or masonry slabs, unless separated from such floors or roofs by an impervious moisture barrier.
- - - 7. Wood furring strips or other wood framing members attached directly to the interior of exterior masonry walls or concrete walls below grade except where an approved vapor retarder is applied between the wall and the furring strips or framing members.

Thank you Jerry. So when referring to wood siding the distance from the soil necessitates the use of preservative treated wood. I cannot just arbitrarily say wood cannot be 6 inches from soil.

Bruce,

I guess I should also have posted the IRC definition of "naturally durable species". There are actually two definitions within the "naturally durable species" definition as it depends on what is being addressed - wood decay or termites: (bold and underlining are mine)

- NATURALLY DURABLE WOOD. The heartwood of the following species with the exception that an occasional piece with corner sapwood is permitted if 90 percent or more of the width of each side on which it occurs is heartwood.

- - Decay resistant. Redwood, cedar, black locust and black walnut.


- - Termite resistant. Alaska yellow cedar, redwood, Eastern red cedar and Western red cedar including all sapwood of Western red cedar.

Originally Posted by JB Thompson

Thank you Jerry. So when referring to wood siding the distance from the soil necessitates the use of preservative treated wood. I cannot just arbitrarily say wood cannot be 6 inches from soil.

Any wood in contact with the ground is required to be either a naturally durable species of wood or be pressure-treated.

Any wood siding, sheathing or wall framing within 6 inches of the ground is required to be either a naturally durable species of wood or be pressure-treated.

Etc for wood in the other specified locations.

The question then arises of "What type of wood is considered to be a naturally durable species?"

The answer depends on the location of the wood - if the wood is in contact with the ground then the answer would be that it needs to resist both wood decay and termites; however, if the wood is not in contact with the ground and an approved termite treatment has been used, then the wood only needs to be wood decay resistant.

If no termite treatment has been used and it is within the clearances specified, then the wood needs to resist both termites and wood decay.

Combining the termite resistant and decay resistant naturally durable species ends up with: the heartwood of Redwood

Yes, "cedar" is decay resistant, but only certain species of cedar are termite resistant. Redwood is the only one listed on both the decay and termite resistant lists.

As a reminder example to this thread:
I recently had a potential customer call me about doing an HI on a new construction. She had some questions about grading concerns. We talked, she said she'd think about it and call me back. She called back a few days later and asked if she could send some pics of the property for me to look at, I said sure. She sent the pics and the development looked really familiar.
The pictures she took weren't great but showed what looked like high grading around a new 'brick' building. We discussed the pictures, she was still concerned and not quite sure about whether she should buy the place or not.
I asked where the building was. As soon as she gave me the address I remembered. I had done a construction assessment for a potential buyer in the same development for about a year ago. The development is a 1 square block site of new single family homes. Concrete foundations, frame with full brick cladding all sides, basement, two story. Not bad looking overall.
The house I looked at about a year ago was the 1st house on the corner. At this point they've built about 7 houses in the row. The current potential buyer was looking at buying the most recent house. Guys were onsite framing the next two houses in 15 degree weather.
The buyer was concerned that the house 'sat low', that gravel along the side was up above the foundation to brick seam. She was worried about water seeping into the house. Her concerns were entirely legitimate. When I went out to the property I saw some very poor design issues that are likely to be issues for buyers.
- The 1st house I looked at a year ago on the corner, sat very nicely above street / sidewalk grade
- All subsequent houses sat lower and lower to each other and related public sidewalk grade
- Gravel between her house and the adjacent finished house was not only above the foundation wall to brick seam but at the top of stone window sills
- Yard dirt at the front wasn't fully finished but was at and above stone sills for the basement windows, and was about 4"-6" below public sidewalk grade
All in all water isn't going to have much choice but to run straight to the walls of these buildings. The buyer decided to pass on the deal.
Besides this being an example of things to look for, I would say there are two primary points to consider:
- Don't forget to think about overall grading issues at new development sites. There tend to be issues that mean nothing in the short term but can pose very negative concerns for owners in the long term
- When driving around for your inspections or on the weekend, if you see a construction site consider stopping, checking it out, and taking some pics. I do this sort of semi-regularly. Its come in quite handy sometimes when I've gotten a call 6 months later from a buyer for an inspection.
Hope this helps.

Originally Posted by Jerry Peck

.......Only certain species of cedar are termite resistant. Redwood is the only one listed on both the decay and termite resistant lists.

It may be advisable to update that rule soon.
Apparently Formosan termites haven't bothered to translate the code book, so they are being discovered eating Cedar, and they will go for Redwood too if they can find it.

Originally Posted by John Kogel

It may be advisable to update that rule soon.
Apparently Formosan termites haven't bothered to translate the code book, so they are being discovered eating Cedar, and they will go for Redwood too if they can find it.

With Cedar it is quite possible that the species of cedar they are eating is not one of the species listed as naturally durable for termites - if one of the other species of cedar, yeah ... hoo-boy supper time is here!

Have you seen where Formosan termites are eating heartwood Redwood? Remember, it is not just the species of wood which is listed, it is the heartwood, not the sapwood, of it, and only 10% or less of one area is permitted to be sapwood.

Originally Posted by Jerry Peck

Bruce,

I guess I should also have posted the IRC definition of "naturally durable species". There are actually two definitions within the "naturally durable species" definition as it depends on what is being addressed - wood decay or termites: (bold and underlining are mine)...

No I understood you. I just left out the "naturally durable" portion because I rarely (read: never) see it around here. Press board, fiber-cement board, MDF, OSB, Masonite and plain ol' pine is really all I ever see sticking into the dirt around here.

Thanks for all of the comments!

Bruce