I watched this interesting video on how to build a Brickhouse from the ground up (seen here) Building A Brick House - YouTube
and they install something called a damp course which is basically a strip of tar paper on the second or third brick up. My question is twofold. On the brick houses in my area. I don’t see any damp course, wouldn’t it stick out a little bit from the Masonry? I’m also wondering do they use a damp course on cinder block or concrete houses? I would also wonder because a lot of concrete and cinder block houses are only one course of cinder blocks and in that video There is two courses of brick wall with a one-inch gap for moisture to evaporate. It seems like in the cinder block houses because they are only one course of cinder blocks that moisture would come in sideways through the wall when it rains, especially in a place like Miami, where it rains a lot and most houses are cinder block. I would think it would be enough moisture to make the wood furring strips used to attack the drywall moldy.
does anyone know? if you watch that youtube video it will make much more sense. You can skip to 2:29 and it shows what I’m talking about
The damp proof course is to halt ground moisture rising up the walls. I’m not a builder so I can’t explain it with the correct terms, but I imagine that modern slab-on-ground construction has a water proof layer below the slab which includes the base of any wall construction and obviates the need for the dpc (damp proof course).
The rain water will be shed by the walls as it isn’t in constant contact with a damp patch.
The video shows the placement of the horizontal waterproof barrier to be just inside the outer perimeter of the brick making it invisible after the mortar is applied. If you look for it after the wall is constructed you would not see it because the mortar conceals it.
The double wall brick construction is no longer popular because it doubles construction costs for masonry. The method of construction now is masonry veneer consisting of a single layer of brick with corrugated masonry ties sent in the mortar joints and nailed to the outside wall framing. This is done during construction and performed by the mason.
When it comes to capillary action transferred by masonry from ground to structure, it is especially important to prevent this action from block piers in the crawl space or from concrete slabs up to interior framing attached to the slab and a vapor barrier must be installed. For block piers supporting floor framing in a crawl space, the vapor barrier is usually a simple piece of metal flashing set between the top of the pier and wood framing it supports. The top or bottom of slabs are normally covered with heavy duty polyethylene prior to framing the structure or pouring the slab and some are also treated with a waterproof sealant.
Isn’t the cinder block hollow ,or ducted, so that it air flows up through the holes and dries it from the inside, and this prevents the inside of it becoming saturated by a wet week (month , year… )
My house (in the UK) is built of double-walled brick. You can see the damp-proof course if you know where to look, but it’s not very obvious. Maybe a millimetre or so of the membrane protrudes from the mortar.
Here’s a pic (not mine!) showing the sort of thing you see. Houses built this way should also have airbricks (perforated bricks like this) just below the damp-proof course that allow ventilation of the wall cavity.
Incidentally, whoever laid the patio at the back of our house screwed up, as the patio is almost exactly level with the DPC, rendering it pretty useless. We don’t seem to have any damp issues though, despite it having been that way for decades. Not recommended, though.
The phenomenon is called “rising damp”. I once restored an old brick building with no moisture barrier, and rising damp was a curse for me.
Even though the inside of the block may be hollow, moisture could continue to flow through the solid outside walls of the block and transfer to the structure.
blocks are hollow because less material is needed for the strength given resulting in lower cost and less weight. these hollow spaces are also involved in locking the wall together. in the end little continuous space is left for air flow.
As a rule of thumb, all “waterproof” barriers in low parts of construction are poor solutions for any but exceptional humidity (though some highly technical solutions can be implemented by specialists, generally at great cost)
Natural flow, and hard rock fill keep the water pressure away from the structure. All waterproof layers will create capillarity, pushing humidity upwards, and condensation on the cold side.
Care in conception, consulting with local specialists will save cash and future problems.
Flashing and well made layer barriers are best for eliminating rainfall penetration into vertical surfaces (as is correct grouting between bricks or stones)
Permanent barriers are used for insect control, but once again, if not properly installed, they will cool down flooring due to condensation.
so is a damp proof course part of the building code for a concrete block house?
Building codes vary by location. Where are you?
Miami, fl
Well I work as a Building Inspector, but I don’t work for your jurisdiction, nor do I know the Building Codes for your location.
I am reasonably familiar with the International Code Conference family of codes, foundation damp proofing has been required in the relevant I-codes since their inception. It was previously required in the BOCA codes. BOCA being one of the code writing organizations joined with others to form the ICC.
I am unfamiliar with damp proofing between masonry courses, foundations locally are almost exclusively poured concrete and the damp proofing is applied to the outside. The very few CMU foundations I recall also had the damp proofing applied on the exterior.
The adaption of a Building Code is very much a State by State issue. Many States adopt Building Codes, others do not. Your best source of information may be your local Building Department, but again depending on where you are, you may not have one. If the State where you live has a web site, and most do, you might try searching for Building Codes there.
You could also check out the ICC web site, they may list a Building Code for your State as they publish State specific versions. The Model Codes are all copy written and while they are available on line, expect to pay for the privilege of reading them.
Your local Library may have a copy in their reference section, but don’t expect to be able to check it out. The Model Codes are expensive.
zuer-coli