Insulating slab-on-grade foundations is essential for preventing excessive heat loss and gain through exposed concrete. To achieve this, it is recommended to clean the exposed slab edge, apply damp proofing as a capillary break, and install non-moisture-sensitive rigid foam board insulation (such as extruded polystyrene (XPS) or mineral wool) along the edge of the slab. This will meet or exceed the insulation R-value required by code.
In cold climates, most slab-on-grade foundations include perimeter stemwalls (or frost walls) that extend 3 ft. or 4 ft. below grade. The area between the stemwalls is usually filled with compacted gravel. Insulating an existing concrete pad typically involves a vapor barrier, foam insulation designed for concrete, special insulation tape, and a new subfloor.
1-2″ of slab insulation around the perimeter and R-25-30 exterior walls is all you need for a comfortable, cost-effective structure. General steps for installing slab insulation in monolithic slabs with grade beam construction include installing rigid insulation on the exterior that extends to the bottom of the grade beam, and securing a protection board over the slab.
Adding insulation outside of the slab edge allows the inside surface temperature of the slab perimeter to more closely track interior conditions, reducing the potential for condensation. Installing perimeter under-slab and edge slab insulation in all concrete floors is good practice. The two most commonly used options for slab edge insulation are thermal insulation and metal flashing or durable finish for protection.
Perimeter insulation for concrete slabs refers to the practice of insulating the outer edges or boundaries of a concrete slab or foundation. Maximum benefit would be placing insulation around the slab perimeter and below the slab in the area adjacent to the perimeter. Engineers require integrated rebar ties to walls around the entire slab, with 3′ rebar stingers bent at 90° to tie into the slab.
📹 The Detail You Didn’t Know You Wanted. Perimeter Sub-slab Insulation.
The house build continues and in this video I touch on a helpful perimeter insulation detail I picked up from reading on green …
Is slab edge insulation worth it?
In winter, the deep ground temperature under a slab is 14 degrees, resulting in a 6 degree temperature differential. This is due to the large area of the slab base and the fact that concrete is a good conductor, causing significant heat loss to the ground. Insulating under the slabs is recommended, which usually earns at least 1/2 a star in the rating. A cost-effective solution is to design the integrated slab with a waffle pod construction, which creates an R0. 7 between the slab and the ground, slowing down heat loss. This allows sunlight to radiate into the living space into the early morning hours.
On the side of the concrete, the night air may be much lower than under the slab, creating a 15-20 degree temperature differential and faster heat flow to the slab sides. Additionally, slab sides typically go uninsulated, creating a thermal bridge around the house footprint. This issue is currently impossible to quantify due to the inaccuracy of house energy rating software. Slab edge insulation is a compulsory element for in-slab heating installation.
Can exterior foam insulation cause mold and moisture problems?
The study explores retrofit approaches for Interior Alaska, focusing on three key questions: whether a double vapor barrier causes moisture problems in the dry Fairbanks climate, if there is a minimum thickness of exterior insulation to prevent condensation problems, and the most “materials efficient” way to retrofit an existing home with exterior foam. The foam acts as a second vapor barrier outside the wall, trapping moisture in the walls and potentially leading to mold and rot.
How to insulate the perimeter of a slab?
Two principal methodologies exist for the installation of slab insulation. The first entails the direct application of rigid insulation to the exterior surface of the slab and footing. The second involves the construction of a “contained” or “floating” slab with interior insulation.
How to insulate the edge of a concrete slab?
It is recommended that the slab be insulated in both vertical and horizontal orientations, with rigid insulation installed to create a bond between the slab and the foundation wall. Additionally, a protective membrane should be adhered to both the slab and the foundation wall.
Where does perimeter insulation go?
Upstand insulation is crucial for insulating concrete floors, installed vertically around the floor perimeter and level with the floor screed. It should be butted up to the bottom of the insulation to minimize thermal bridging. The cavity wall insulation should extend beyond the floor insulation by at least 150mm to prevent insulation failure. The upstand is also essential for installing underfloor heating systems. Poor installation can lead to poor occupant comfort and energy efficiency.
The installation process can be complex, and many architects and engineers struggle to develop simpler methods. To ensure the right level of insulation, it is essential to monitor key areas and ensure the correct level of insulation is provided.
What is the downside to foam insulation?
Spray foam insulation can be a potential source of mold growth if not properly installed. Proper moisture control and ventilation are crucial for effective mold management. Additionally, some spray foams can cause respiratory problems during installation and curing, and off-gassing can lead to indoor air quality issues. Proper installation and curing times, along with understanding how foam off-gasses, can mitigate these risks.
Considering the long-term effects of spray foam insulation is essential, as it can reduce energy costs but also impact a home’s resale value. Therefore, homeowners should consider these factors when choosing insulation for their homes.
Is it better to insulate above or below concrete slab?
It is recommended that insulation be applied below the concrete layer, as this method is more effective than insulating after the concrete has been poured.
What would you recommend for insulating a concrete slab floor?
Concrete floors frequently employ radiant foam insulation, rigid foam boards, and fiberglass floor foil.
What material is used for perimeter insulation?
Rigid foam boards like extruded polystyrene and expanded polystyrene are popular for perimeter insulation due to their thermal efficiency, moisture resistance, and cost. When choosing a material, consider factors such as the H1 climate zone, R-value, material and installation costs, retrofit or in-situ application, moisture resistance, longevity, access to the product, potential supply chain disruptions, and environmental impact. These factors help determine the best choice for insulation in specific projects.
How to fit perimeter insulation?
Building control is a crucial aspect of any building project, requiring approval from the local authority. It involves the use of full sheets with a straight edge against the external wall and offcuts to make up the fit against internal walls or the center of the floor. The process of building control can vary depending on the type of application needed, the cost, and the size of the project.
When applying for building control approval, it is essential to consider factors such as the expiry of an Approved Inspector’s insurance, the need to inform neighbors about the work, obtain a copy of the approved documents, and apply for approval. Penalties for non-compliance with building regulations can be severe, especially if the work was carried out before the owner owned the house.
Some common types of building projects that require building control approval include loft conversion, garage conversion, extension, conservatory, electrical work, internal alterations, basement, and porch. Approved inspectors may face problems once their insurance has expired, and the process for transferring work from an AI that no longer has insurance to an LABC team can be complex.
The project must be reverted to the local authority, and the cost of canceling an initial notice and reverting work to the local council can be high. The local authority surveyor will also be involved in this process.
In case of an Approved Inspector failing to secure renewal of their insurance, a cancellation notice may be issued, and information should be requested when reverting a project to the local council. The government and LABC are working to help in this situation, and further information and updates can be obtained.
How thick should perimeter insulation be?
Building control is a crucial aspect of any building project, requiring approval from the local authority (LABC) to ensure that the project is safe and compliant with building regulations. The process involves submitting a building control application, which can be either planning permission or building regulations. The cost of building control applications varies, but it typically takes around two years to complete.
When applying for building control approval, it is essential to consider factors such as the type of building work, the need for permission for building work, and the potential penalties for non-compliance. If you are considering selling your home, you may need approval for building work carried out before you owned the house.
Some private building inspectors may face problems due to the expiration of their insurance, and the process for transferring work from an AI that no longer has insurance to an LABC team can be complex. The project must then be reverted to the local authority, and the cost of canceling an initial notice and reverting work to the local council can be high.
Approved Inspectors may continue without the required insurance, and any regulatory work done during this period may not be covered. A cancellation notice may be issued by the Approved Inspector, and information should be requested when reverting a project to the local council.
The government and LABC are working to help in this situation, providing further information and updates on building regulations.
📹 The RIGHT WAY to Insulate Your Concrete Floor
If you are building a new home, do not forget to insulate your concrete floor. Whether you have a slab-on-grade home, or a home …
It was my plan how to renovate my basement apartment. I have to brake concrete slab along foundation wall to dig down to footing to place xps board or I dig under the slab to place insulation there only actual digging could tell which method would be easier for me. As well as some one who lived in Europe in cold climate and familiar with their construction methods I would say you do not need to insulate entire slab, if you insulted perimeter of foundation down below frost line all soil underneath of your house would work as insulation unless if you have ground water close to surface
i like the chamfered edge. Great idea. Not sure how flat you got the gravel under your insulation. Looks like it undulates a bit. I have been suggested to use a 2″ sand topper or use 1/2″ crushed so it’s easier to screed flat so to eliminate voids under the insulation. 10 mil visqueen over the insulation and over the top of footing at foundation bolts.