Frequently Asked Questions about Insulated Concrete Forms

General Questions

1. What is Quad-Lock?
Quad-Lock products are lightweight, insulating, stay-in-place concrete forming systems ("insulated concrete forms" or "ICFs") for walls, floors, and roofs - combining numerous construction steps into a single assembly ready for utilities and finishes. Also see Insulating Concrete Forms Explained and Insulating Concrete Forms Construction Overview.

2. What can you build with Quad-Lock?
Resilient, sustainable, cast-in-place concrete buildings with superior insulation and high durability. Use Quad-Lock walls for basements/foundations, exterior above-grade walls, fire walls, and more in residential, commercial, and institutional construction. Use Quad-Deck floors & roofs to complete the building shell with reinforced concrete bunker-technology.

3. Does a Quad-Lock building cost more?
Overall, Quad-Lock buildings provide a much better value. Much lower recurring costs and higher resale values easily pay for slightly higher construction costs - without even considering the effects of healthy, safe, and peaceful interior spaces. See Financial Analysis / Incentives.

4. How high can I build?
Multi-storey structures can be built with Quad-Lock, one storey at a time. Each storey is stacked 8'-12' high [2.4-3.6m] and poured in 2'-4' lifts [60-120cm] in a continuous pour.

5. Do the forms stay on after the concrete is poured?
Yes, the EPS stays in place to provide insulation, space to run utilities, and a surface to install finish materials like gypsumboard, stucco, stone, brick, and siding.

6. Will it take longer to build with Quad-Lock?
Experienced Quad-Lock crews can actually build ICF structures in less time compared to wood-frame construction because ICFs combine numerous construction steps into one step: structural framing, sheathing, insulating, furring, vapor barriers and air barriers.

7. How is a Quad-Lock wall different from a wood frame wall?
High-mass, reinforced concrete walls built with Quad-Lock are usually 8.5 times stronger than wood-framed cavity walls. They also are a better sound barrier (STC Rating of 50+); more resistant to natural disasters, rot, and termites; better insulated (superior R-value) and, therefore, more energy efficient; they reduce air infiltration and the thermal mass of the concrete keeps inside temperatures more even.

8. How is Quad-Lock different from other Insulating Concrete Forms?
Quad-Lock is extremely versatile with the highest available true R-value of up to R-59. Quad-Lock offers a complete wall forming solution with track, brackets etc. - not just the foam. Quad-Lock provides excellent support, is ISO 9001 and 14001 certified, and costs less to ship and store. See Quad-Lock Advantage for more details.

9. Is building with Quad-Lock easy to learn for a builder?
Yes. Quad-Lock installers find it is easy to transfer basic building skills to Quad-Lock. Experience in carpentry, masonry, and concrete forming and placement are particularly helpful. Quad-Lock offers detailed instructional and technical materials for builders, such as the Quad-Lock installation video, product manual, installation guide, and technical bulletins. Quad-Lock and our distributors sponsor training seminars and introductory events. Quad-Lock also provides technical assistance via phone, email, online and in some cases on-site.

System & Wall Characteristics

10. What are Quad-Lock's physical dimensions?
Each panel is 48" long, 12" high [1218 x 305mm] and 2¼", 3.125" or 4¼" thick [58, 79 or 108mm]. The ties are available in six standard sizes creating various concrete thicknesses, and even thicker walls can be built using the Extender Tie. See Products.

11. What is Quad-Lock made of?
The panels are made from safe, non-toxic, fire-retardant EPS (expanded polystyrene) and the ties are made from HDPE (high-density polyethylene). Quad-Lock panels contain no CFCs, HCFCs, polyisocyanurates, or other toxic chemicals. They do not "off-gas" under normal use nor break down over time.

12. Can I remodel or add to a Quad-Lock building later?
Yes. Openings can be cut into concrete walls with tools obtainable from most tool rental stores. You can also add more walls by connecting them to existing walls.

13. Is a Quad-Lock building safer than a wood-framed building?
Yes, reinforced concrete walls are up to 8.5 times stronger than wood-framed buildings. As a result, Quad-Lock walls can be far more resistant to earthquakes, tornadoes, and hurricanes when designed appropriately. In addition, Quad-Lock walls have been tested to have 2-4 hour fire resistance ratings. Quad-Lock walls, however, are only one component of the building so you should make other building components disaster resistant as well, e.g. with concrete roofs and floors.

14. What happens to Quad-Lock products in a fire?
Concrete structures are far more likely to remain standing through a fire than structures built with wood: Quad-Lock walls have been tested independently to have a 2-4 hour Fire Resistance Rating due to the solid concrete within. In the same tests wood-frame walls typically collapse in one hour or less. To allow safe evacuation per building codes, Quad-Lock products are finished with a 15-minute thermal barrier such as ½" [13mm] drywall on the interior, see Quad-Lock's NFPA 286 / ISO 9705 tests. If finished appropriately on the exterior e.g. with cementitious stucco and metal roof finishes, Quad-Lock buildings are less likely to be affected by wildfires or ember. Quad-Lock products are made from EPS with fire retardant qualities which shrinks away from the heat when exposed to ignition energy, and it self extinguishes as soon as the ignition source is removed. See Fire Safe Construction with EPS.

15. Are Quad-Lock walls more resistant to rot and mold?
Yes. Quad-Lock walls themselves offer no medium for rot or mold to occur because they are solid, high-mass construction, with concrete filling the entire cavity of the forms. Concrete, steel, and EPS are all inert materials that do not rot nor sustain mildew.
However, drywall contains paper which can support mold when combined with excessive moisture. So interior moisture should be controlled using spot removal (e.g. bathroom fans) and properly sized air conditioning units that will cycle long enough to dehumidify the air. In the first few months after construction, additional dehumidification might be necessary in Quad-Lock buildings.
Most wood-framed buildings are so susceptible to rot and mold because moisture can get trapped inside the open cavity of the walls despite a patchwork of house wraps, seals, caulk, tapes, and gaskets. The moisture combined with the organic materials allows mold and mildew to develop and rot to occur.

16. What about termites, ants, and other pests?
EPS provides no food value for termites, ants, or other pests, but they can nest in and channel through the foam. The solid concrete, however, stops them and, unlike wood, the structural integrity of the building won't be affected. As in other types of construction, local building codes require protecting the foam, especially in high termite infestation areas, which are listed in the International Residential Code. Quad-Lock offers peel & stick termite and waterproofing barriers for below-grade protection. When using Quad-Lock below and above grade, a minimum 6" bare concrete inspection strip at grade level is highly recommended to force termites to the outside of the foam where they will be visible.

Design, Engineering & Building Codes

17. What wall thicknesses can be built with Quad-Lock?
Nominal Concrete Thicknesses of 4", 6", 8", 10", 12", 14" can be built using standard Quad-Lock components. Walls of greater width (in 2" increments) can be built using the Quad-Lock Extender Tie. See Quad- Lock Ties.

18. How do I determine what size Quad-Lock wall to build?
This is a decision to be made by your local building department based on prescriptive designs, or by a licensed engineer. The local building department may allow you to follow pre-approved prescriptive designs, such as the International Residential Code (IRC). See Guide to Code Compliance.

19. Does the job need to be engineered?
In today's regulatory environment, many buildings require some engineering, but check with your local building department. Quad-Lock's flat, monolithic concrete walls may conform to pre-approved prescriptive designs available from the local building department.

20. Do local building departments accept Quad-Lock?
While final approval is up to the local building official, Quad-Lock has completed code-evaluation reports in the USA, Canada and elsewhere which are often recognized by local officials. Quad-Lock forms solid, flat, monolithic concrete walls, and, therefore, can emulate prescriptive designs that are pre-approved by local building departments. Please refer to the Guide to Code Compliance for more details.

21. Do I need a home plan specifically designed for insulating concrete forms?
No. Because of the flexibility of the Quad-Lock system, it is not necessary for you to choose a house plan designed just for ICFs. In almost all cases, you have the freedom to choose a house plan from any design company and the Quad-Lock materials will adapt to those drawings. The plans, specifications and measurements should be checked by a design professional to ensure that the higher wall thicknesses are properly accounted for.

Doing Business with Quad-Lock

22. How much does Quad-Lock cost?
Quad-Lock products vary in price largely depending on chosen configuration and freight. Quad-Lock materials are estimated based on the actual components needed for your particular project PLUS a typical waste-factor (important!). Contact us for an estimate. We'll need your plans (floors and elevations) or exact wall dimensions - incl. wall lengths, heights, and thicknesses; sizes of all wall openings; numbers of corners/angles/T-walls etc. See Get a Quote.

23. How do I find skilled labor to construct my Quad-Lock building?
Contact your local Quad-Lock dealer for referrals to contractors experienced with Quad-Lock. Quad-Lock also provides training seminars for contractors.

24. How do I find an Architect or Engineer familiar with Quad-Lock?
Contact your nearest dealer and they can usually recommend an architect or engineer in your area who is familiar with designing with insulating concrete forms. Quad-Lock's Technical Library makes it easy for design professional to incorporate ICFs.

25. How will my Quad-Lock project be supported?
Not only is your local dealer equipped to answer your questions and assist at the jobsite but your local Quad-Lock Field Representative is also ready to assist with quantity take-offs, job site training, product seminars and dealer training.

26. How long does it take to receive Quad-Lock materials from my dealer?
Most Quad-Lock dealers keep an inventory of common Quad-Lock materials. Sometimes their supply might be limited but they can place an order with the Quad-Lock factory and usually receive their order within a week or two (in North America, longer elsewhere).

27. What kind of warranty does Quad-Lock provide?
We offer a limited product warranty for defective products.

Quad-Lock Construction

28. How much bracing is needed?
Enough to keep the wall aligned during stacking and pouring, generally every 4-6' [1.2 - 1.8m]. The corner and angle brackets eliminate the need for structural bracing of corners and angles. Refer to the Quad-Lock installation video, product manual or your local Quad-Lock dealer for more details.

29. Is a special concrete mix used?
With ICFs now commonly used in most areas, the local Ready-Mixed Concrete producer will probably have an "ICF Mix" pre-designed and available. The information that the supplier needs is:
1) The specified compressive strength from the building plan;
2) A minimum 6" [150mm] slump (6" to 6.5" preferred);
3) The need for highly "flowable" concrete (e.g. with super plasticizer);
4) Aggregate Size of 3/8" [10mm] or 3/4" [20mm] (for walls 8" thick or more) and
5) What type of placement equipment is being used (concrete pump, conveyor, etc).
The concrete supplier will determine what mix of locally available materials will give you the best performance.

30. Do the walls need to be vibrated?
Yes, always use proper placement and consolidation techniques, including using a mechanical vibrator with a small diameter (e.g 1¼" [32mm]) - even when using high slump concrete (with super-plasticizer). To prevent segregation, do NOT over-vibrate. See Product Manual.

31. How are doors and windows installed?
A wooden or vinyl frame (or "buck") is built to the specified size of the window or door rough opening and then inserted into the Quad-Lock wall. The buck is secured into place and concrete is poured around it. Refer to the installation video and product manual for details.

32. How is electrical and plumbing installed?
Most electrical and plumbing is set into chases cut into the foam after the concrete has set. Electrical boxes, supply lines, and drain lines are affixed directly to the concrete after cutting the foam away. Electrical conduit and some plumbing may also be placed within the wall cavity prior to concrete placement. Refer to the installation video and product manual for suggestions.

33. How is drywall attached?
Drywall is fastened to the Plastic Ties within the foam with drywall / gypsum screws every 12". An EPS compatible adhesive may be used in addition.

34. How are exterior finishes attached?
Stucco can be adhered directly to the foam (after rasping it) per the stucco manufacturer's recommendations, usually requiring a mesh. Wood, plastic or metal cladding is mechanically fastened to plastic ties or, if needed, to "airgap strips" or the continuous fastening strips within the Quad-Lock FS panels. Stone and brick are attached according to design specifications (e.g. with brick ledges and brick ties).

35. Do Quad-Lock walls below grade need water-proofing or damp-proofing?
Yes, just like any concrete structure that is exposed to moisture and potentially to hydrostatic pressure. Depending on the site conditions Quad-Lock recommends water-proofing or damp-proofing with peel & stick membranes and/or drainage boards. In addition, Quad-Lock recommends following all other accepted methods for water management, such as proper drainage, compaction of backfill, and management of run-off for the entire site. Refer to or our ICF Accessories or product manual for suggestions.

36. Is a vapor barrier still required for above-grade Quad-Lock walls?
No. Quad-Lock ICF walls are 'High Mass' walls (as opposed to Cavity walls like wood-frame) which don't need vapor barriers. And the low permeance of the foam and concrete provide a natural barrier against air-borne moisture and air infiltration. This also means that air-borne pollutants, dust, and pollen are kept out of the building by Quad-Lock building shells.

Still have questions? Please contact us.