Ways To Insulate Radiant Exterior Slab?

In this video, Jake discusses the importance of proper insulation for a slab-on-grade foundation. He explains how to properly insulate a slab with expanded polystyrene, extruded polystyrene, or polyisocyanurate, and how to calculate the R-value needed for a radiant slab. He also discusses the benefits of slab edge insulation, which is crucial for energy efficiency and occupant comfort.

To create a continuous thermal boundary with rigid foam and raft floor, he recommends unrolling the under slab insulation, extending it approximately 6 inches up the side walls, and sealing the seams. Then, he suggests using 2″ rigid XPS (insulating vertically at the edges) to isolate the radiant from the concrete sub floor slab.

There are two primary contenders when it comes to under slab insulation: Expanded Polystyrene (EPS) and Extruded Polystyrene (XPS). The standard procedure is to compact the soil and gravel base, lay styrofoam EPS down, and glue together. Some EPS have built-in radiant pipe channels, and you can lay the EPS down. To isolate the radiant from the concrete sub floor slab, he suggests 2″ rigid XPS (insulating vertically at the edges), then lay the pex on the XPS. Another option is to run a 2×2 on top of the regular insulation, providing a thermal break and possible tack strip.

In summary, proper insulation is essential for a slab-on-grade foundation to prevent freezing and maintain structural integrity. By using the right amount of insulation, the ground can be kept from freezing without the need to heat the ground from above.

How do you insulate against radiant heat?

Radiant barriers are highly reflective materials, typically aluminum foil, applied to substrate materials like kraft paper, plastic films, cardboard, and air infiltration barrier material. They can be combined with various insulation materials to form thermal insulation’s facing material. The effectiveness of radiant barriers depends on proper installation, so it’s recommended to use a certified installer. If installing yourself, follow manufacturer’s instructions and safety precautions, and check local building and fire codes. The reflective insulation trade association offers installation tips.

How do you insulate an exterior slab?

To insulate slab foundations, remove dirt, clean the exposed slab edge, and apply damp proofing. Install non-moisture-sensitive rigid foam board insulation along the slab’s edge to meet or exceed the required R-value. Install from the top of the slab down to the depth required by code, unless a termite inspection gap is required. Cover any exposed insulation with metal, cement board, or cellular PVC panel. If cement board is used, it should be non-reinforced with wood fibers or coated with acrylic latex paint to protect it from water damage.

Install a metal cap as an insect guard, sealing the cap to the slab edge with mastic. Replace the backfill, sloping away from the building. For more information on insulating slab foundations and safe work practices, refer to the U. S. Department of Energy’s Standard Work Specifications and the Compliance Tab.

How do you insulate an exterior concrete foundation?

The process involves cutting away an exterior concrete block foundation wall, including the footings and excavated ground around the house. Rigid drainage-type insulation is attached vertically to the wall and extends from the top to the footings. A drainage tile is essential along the footings at the base of the foundation, surrounded by gravel. The insulation is measured and cut to the desired height, starting at one corner, overlapping at the corners, and keeping the sheets as tight to the wall as possible. Some experts suggest using two layers of insulation with overlapping joints, which are held in place at the top edge by the flashing and corrosion-resistant fasteners and washers.

How to insulate a slab for radiant heat?

To install insulation under concrete, follow these steps:

1. Lay down the insulation by extending it 6 inches up the side walls.
2. Seal the seams between rolls with white adhesive insulation tape to maintain the insulation’s 100 vapor barrier.
3. Add 1″ of sand to facilitate water drainage and reduce curing time.
4. Pour the concrete as usual after placing and sealing the insulation. \nNote: Check local building codes for compliance before installation. This instruction is not intended to illustrate proper construction methods, which are the responsibility of the builder or contractor.

Is it worth insulating the exterior foundation?

Foundation walls should include waterproofing and protection board, along with structural components like concrete or masonry, to keep water out. Foundation foam insulation on the exterior side provides a buffer zone for the waterproofing from backfilled soil. This insulation layer typically consists of one or two inches of foam board like extruded polystyrene or polyiso. Moving foundation wall insulation to the exterior side can save on building materials as it doesn’t require an expensive finish on top.

Insulating foundation walls from the outside increases the building’s usable square footage, resulting in a lower price per square foot and a higher value to the occupants. For example, a 10’x10′ room with 2″ insulation on each wall would have 100 SF when insulated on the exterior, but 93 SF when insulated on the interior.

Should radiant barrier be inside or outside insulation?

Radiant barrier installation is a method to convert heat into radiant form, allowing it to be redirected back to its source. The best way to convert heat to radiant form is to cross an air space, making the barrier most effective when placed closest to the outside of the wall. This method is similar to the cathedral ceiling method, but with the foil closest to the outside layer while maintaining an air space on one side. For remodeling walls with shared exterior sheathing, retrofit/remodel instructions are provided.

For new construction, consider using a radiant barrier house wrap outside the wall, between the brick/stone/siding and exterior sheathing. The exterior of a west-facing wall can reach over 150º on a hot-sunny afternoon, as the wall absorbs radiant heat from the sun and heats up. Traditional insulation only slows down heat flow by conduction, not stopping it.

Do you need vapor barrier under exterior slab?

Water beneath buildings is invisible to the naked eye, but water vapor can damage the foundation, subfloor, and main floor. A vapor barrier is essential to protect building materials from the negative effects of water vapor. Without a vapor barrier, concrete deteriorates faster due to water vapor intrusion, leading to foundation and building failures. The American Society for Testing and Materials (ASTM) outlines national standards for underslab vapor barriers, with ASTM E1745 specifying Class A vapor barriers for underneath concrete slabs.

The lack of a vapor barrier can lead to water intrusion, unstable foundations, and cracked slabs. The lack of a vapor barrier can lead to major disasters like the Surfside Condominium Collapse in Miami, Florida.

What is the best insulation under a concrete slab?

XPS foam insulation boards are popular for under-slab applications due to their high compressive strength, moisture resistance, and durability. They are ideal for areas with high groundwater levels. Polyisocyanurate foam boards offer excellent thermal insulation with foil facings. ISO insulation is known for its high R-value and fire resistance. EPS foam insulation is lightweight and cost-effective, but may not offer the same compressive strength as XPS or ISO. It is often used in less demanding under-slab applications.

Can I put foam board on my outside foundation?

Subterra or Subterra Plus is an ideal insulation product for exterior foundation wall applications, featuring an energy-efficient and long-lasting Graphite Polystyrene (GPS) foam core with an R-value of R-5 per nominal inch. The foam is shielded from ground moisture by a thick polypropylene layer, acting as both a thermal break and a protective barrier for the waterproofing membrane. Insulating a foundation wall from the outside is always a better idea for two key reasons.

Does aluminum foil block radiant heat?

Aluminum foil is an effective insulating material due to its ability to prevent heat from radiating out into the environment, rendering it suitable for use under a roof. Although it warms up through conduction from shingles, it does not radiate heat into the attic space, which makes it ideal for use in HVAC applications and other residential and commercial applications.

Can you put insulation on top of concrete slab?

The insulation of concrete below the concrete layer is the preferred method, as it allows the slabs to absorb heat, thereby reducing the likelihood of overheating and facilitating the effective absorption of heat by the concrete.