How long does it take a slab to dry out before flooring can be installed?

This is a very important question. Moisture is a problem with fresh concrete slabs, and if you install your floor in a wet slab you will have a lot of problems in the future.

Basement Finished Superior Wall1
Concrete slab in the basement after finishing. We are now around 2 months after the installation. The concrete walls are already insulated (we used Superior Wall pre-cast foundations in this project)

Variables that affects the concrete moisture include:ambient relative humidity, concrete permeability, amount of water in the concrete when it is placed, slab thickness, presence (and thickness) of a vapor barrier in contact with the slab bottom, and method used to finish the surface.

Here you have the needs depending on the type of floor to be installed:

  1. Impermeable flooring (Vynil, for example): Internal relative humidity around 85% or surface moisture–vapor emission rates (MVER) of 3-5 pounds of moisture per square-feet over 24 hours
  2. Wood floors: 75% internal relative humidity and an MVER of 3 pounds of moisture per square-feet over 24 hours (National Wood Flooring Association recommendation)

In practical terms, just remember that to achieve the recommendations it takes time. In normal average conditions (relative humidity around 50% most of the time and temperature above 65F, concrete water-cement ratio of 50%) a 4-inch slab can take up to 3 months to dry before you can apply a floor there. But remember that this 3 month period starts only when the cement is dry.

You have some specific tests for that, that are too technical to describe here. Just to mention, the calcium-chloride test and the internal relative humidity test are tow that can be applied for this evaluation.

One of the most important features is the vapor barrier/vapor retarder. Without a vapor barrier the slab will never dry out. That’s why the construction codes put the obligation to use a 6 mils vapor barrier there. The 10mils and also the 15 mils poly sheet can better control the moisture. The best location for the vapor barrier is in direct contact with the bottom of the slab.

If insulation is used over the concrete slab a 4-month drying time should be respected before installing the EPS (normally the EPS absorbs 0.5% by volume).

To have more detailed information about that you can click here and check the Concrete Construction magazine

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Engineered Wood Products: the new normal

Engineered wood products includes a range of derivative wood products which are manufactured by binding or fixing the strands, particles, fibers, or veneers together with adhesives or other fixation methods.

They can be divided in a lot of categories:

  1. Plywood: one of the most recognized and trusted wood building products for decades. Manufactured from thin sheets of cross-laminated veneer and bonded under heat and pressure with strong adhesives, plywood panels have superior dimensional stability and an excellent strength-to-weight ratio and are highly resistant to impacts, chemicals, and changes in environmental temperature and humidity. Suitable for a variety of end uses including subflooring, single-layer flooring, wall and roof sheathing, sheathing ceiling/deck, structural insulated panels, marine applications, siding, webs of wood I-joists, concrete forming, pallets, industrial containers, mezzanine decks, and furniture.
  2. Oriented Strand Board (OSB): widely used, versatile structural wood panel. Manufactured from waterproof heat-cured adhesives and rectangularly shaped wood strands that are arranged in cross-oriented layers, OSB is an engineered wood panel that shares many of the strength and performance characteristics of plywood. OSB’s combination of wood and adhesives creates a strong, dimensionally stable panel that resists deflection, delamination, and warping; likewise, panels resist racking and shape distortion when subjected to demanding wind and seismic conditions. Relative to their strength, OSB panels are light in weight and easy to handle and install. Also suitable for a variety of end uses (similar to plywood)
  3. Glulam: Glued laminated timber, or glulam, is a highly innovative construction material. Pound for pound, glulam is stronger than steel and has greater strength and stiffness than comparably sized dimensional lumber. Increased design values, improved product performance, and cost competitiveness make glulam the superior choice for projects from simple beams and headers in residential construction to soaring arches for domed roofs spanning more than 500 feet. Glulam has a reputation for being used in striking, exposed applications such as vaulted ceilings and other designs with soaring open spaces. In homes, churches, public buildings, and other light commercial structures, glulam is often specified for its beauty as well as its strength
  4. I-Joists: I-joists are strong, lightweight, “I” shaped engineered wood structural members that meet demanding performance standards. I-joists are comprised of top and bottom flanges, which resist bending, united with webs, which provide outstanding shear resistance. The flange material is typically laminated veneer lumber (LVL) or solid sawn lumber, and the web is made with plywood or OSB. The robust combination of structural characteristics results in a versatile, economical framing member that is easy to install in residential and light commercial projects. I-joists are used extensively in residential floor and roof framing. They are ideal for long spans, including continuous spans over intermediate supports. Because I-joists are straight and true, it’s easier for builders to avoid crowning and maintain a level framing surface.
  5. Structural composite lumber (SCL):  includes laminated veneer lumber (LVL), parallel strand lumber (PSL), laminated strand lumber (LSL) and oriented strand lumber (OSL). They represent a family of engineered wood products created by layering dried and graded wood veneers, strands or flakes with moisture resistant adhesive into blocks of material known as billets, which are subsequently resawn into specified sizes. Typical uses for SCL include rafters, headers, beams, joists, studs, columns, and I-joist flange material. Two or three sections of SCL can be joined together to form 3-1/2-inch or 5-1/4-inch members. These thicker sections readily nest into 2×4 or 2×6 framed walls as headers or columns

Source: APA website

Pros and cons of bamboo flooring

Bamboo Floor Wise Home Building
Photo from the website TrinityBamboo.com

Bamboo is becoming a good option for flooring. The majority of today’s bamboo flooring products originate in China and other portions of Asia. Moso bamboo is the species most commonly used for flooring. Although it’s typically referred to as a hardwood flooring, bamboo is actually a grass that’s highly processed to produce flooring and other home improvement products.

All bamboo flooring is engineered, meaning the strands of grass are sliced and shredded, then pressed back together with heat and glues to form the flooring boards.
Bamboo is naturally light in color – a process called carbonization normally darken the surface. Carbonized bamboo flooring is softer than natural bamboo.
The cost of bamboo flooring can vary from $3 to $5 per square foot, a little bit cheaper than most common hardwood flooring types. Pro installation adds another $3 to $5 per square foot.
 
If you’re concerned, look for bamboo flooring products from companies that have been certified by the Forestry Stewardship Council (FSC) for their harvesting and manufacturing practices.

Bamboo Flooring Pros:

  • Top-quality bamboo brands are durable as traditional hardwood flooring. However, not all bamboo flooring is created equal. Look for flooring with a substantial warranty.
  • Bamboo flooring has a contemporary look.
  • Properly finished bamboo flooring cleans easily with a mop and mild soap.
  • They are water resistant
  • You can choose more engineered floors that can be very similar to hardwood flooring

Bamboo Flooring Cons:

  • Take care of inexpensive bamboo flooring: they are susceptible to scratches and dings.
  • Some bamboo flooring absorbs water and is susceptible to damage from water and excessive humidity.
  • Bamboo flooring is limited to a few tonal shades.

Wood and water?

We always heard about problems when wood and water are in contact, correct? If you once had to fix your floor or work in a renovation site you know what I meant. But innovation is there to prove we may be wrong.

Capture Accoya Wood Bath

Accoya project in a bathroom in Sao Paulo, Brazil – Source of the picture – click here

Extensive laboratory and field testing by leading institutes around the world (including in New Zealand, USA, UK, Sweden, Malaysia, Indonesia, the Netherlands and Japan) has shown that Accoya wood performance of acetylated wood is extremely reliable.

But wait: what is the meaning of acetylated wood? The process alters the cell structure of wood, improving its technical properties and making it much stronger and more durable.

Unmodified wood contains ‘free hydroxyl groups’ that absorb and release water as weather conditions change. This makes standard wood susceptible to expansion and contraction, particularly when used outdoors for applications such as cladding, window and door frames. The expansion and contraction of wood often leads to splitting and rotting, impacting on the service life of wood.

Hydrogen, oxygen and carbon chemicals (called acetyl groups) are created within wood after the acetylation process, changing the structure of existing free hydroxyl groups (hydrogen and oxygen). Each of these chemicals is present naturally in all woods, with acetyl created independently from acetic acid, i.e. vinegar. The process is ‘green’ meaning that the acetylation process takes effect using nothing that doesn’t occur in wood naturally.

Accoya® treated wood has been thoroughly tested for dimensional stability, durability, paint retention and in-ground conditions to ensure optimal performance. Indeed, it is so reliable that for many years it has been – and continues to be – used by scientists as the benchmark against which other treatments and modified timbers are measured.

Accoya®’s producers ensure that every batch is of consistent quality and reaches the highest performance standards. With such strong scientific credentials, Accoya® is guaranteed for 50 years when used above ground, and 25 year when used for below-ground applications.

Time will tell if the more expensive price will justify the long term benefits of this process.

Explore more of the beauty of Accoya® wood projects all over the world in their website: https://www.accoya.com/