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Permeability can be reported in perms, a measure of the rate of transfer of water vapor through a material (1.0 US perm = 1.0 grain/square-foot·hour·inch of mercury ≈ 57 SI perm = 57 ng/s·m 2 ·Pa). American building codes started classifying vapor retarders in the 2007 IRC supplement.
A damp-proof course (DPC) [2] is a barrier through the structure designed to prevent moisture rising by capillary action such as through a phenomenon known as rising damp. Rising damp is the effect of water rising from the ground into property. [3] The damp proof course may be horizontal or vertical. [4]
Damp proofing is another aspect of waterproofing. Masonry walls are built with a damp-proof course to prevent rising damp , and the concrete in foundations needs to be damp-proofed or waterproofed with a liquid coating, basement waterproofing membrane (even under the concrete slab floor where polyethylene sheeting is commonly used), or an ...
A variant of the metric perm is used in DIN Standard 53122, where permeance is also expressed in grams per square meter per day, but at a fixed, "standard" vapor-pressure difference of 17.918 mmHg. This unit is thus 17.918 times smaller than a metric perm, corresponding to about 0.084683 of a U.S. perm.
Damp-proofing rods are available with BBA approval. The rods are placed into holes drilled in the mortar course and the active ingredients diffuse along the mortar line before curing to form a damp-proof course. [53] Damp-proofing rods are usually supplied in 180mm (7") lengths suitable for inserting into a 9-inch thick wall.
The purpose of a Vertical Damp Proof Barrier is to prevent the ingress of damp and water into subterranean structures such as basements, cellars, tunnels and earth shielded buildings. (Also known as Earth sheltered buildings ).
Meteorological data includes wind speeds which may be expressed as statute miles per hour, knots, or meters per second. Here are the conversion factors for those various expressions of wind speed: 1 m/s = 2.237 statute mile/h = 1.944 knots 1 knot = 1.151 statute mile/h = 0.514 m/s 1 statute mile/h = 0.869 knots = 0.447 m/s
Strengths might exceed the ASTM standard for concrete blocks (1,900 pounds per square inch (13,000 kPa)) in some instances. In India, the observed compressive strength and flexural strength of CSEB at 28 days of aging with 9% cement stabilization has been observed to be 3.2 MPa (464 psi) and 1 MPa (145 psi) respectively. [ 6 ]