ICFPro.ca is a division of ICFhome Ontario - Direct Line 1 705 533-1633 - Email: info@icfpro.ca
Finishing GuideHow to Finish ICF Walls:
How to Finish ICF Walls:
Drywall, Siding, Stone, Stucco and Cabinets
Your trades will ask where they are supposed to put their screws. The short answer is: into the plastic webs, which are hiding under the foam every 6 or 8 inches. Here is how each finish goes on, and the few things that catch people out.
The Short Answer
Every ICF block has plastic or steel fastening strips (webs) every 6 or 8 inches, marked on the foam. Drywall screws, siding, strapping and trim fasten into those. Inside, drywall goes straight onto the foam and is required as the thermal barrier over the EPS. Outside, vinyl and fibre-cement siding screw to the webs, stone and brick sit on a brick ledge or a footing ledge, and stucco goes on with a mesh and a system made for foam. Heavy items like cabinets and TVs need extra blocking, a strap, or a concrete anchor.
Find the Webs First
The webs (also called ties or fastening strips) connect the two foam faces through the concrete. Most brands mark them on the outside of the block. On most blocks they run vertically every 6 or 8 inches and give you a strip about 1-1/2 inches wide to screw into.
Use coarse-thread screws long enough to bite at least 1/2 inch into the web. A screw that misses the web holds about as well as a thumbtack in a marshmallow.
Inside: Drywall and Trim
- Drywall goes straight on. No studs, no strapping, no poly. The foam is the insulation and the vapour retarder.
- It is required. The building code needs a thermal barrier over foam plastic on the inside, normally 1/2-inch (12.7 mm) gypsum board. Do not leave foam exposed in finished space, the garage or the basement.
- Use adhesive plus screws. A bead of foam-safe adhesive and screws into the webs gives a flat, solid wall.
- Trim and baseboard nail or screw into the webs. Mark the web lines on the floor before the drywall goes up.
Cabinets, TVs and Heavy Loads
The webs are fine for drywall and pictures. For upper cabinets, a big TV, a wall-hung toilet or shelving full of books, plan ahead:
Wood strips in the foam
Before drywall, cut a channel in the foam and glue in a 1x4 or plywood strip screwed to several webs. Cheap and strong.
Concrete anchors
For real weight, go through the foam into the concrete with sleeve anchors or concrete screws. Use the right length.
Embedded ledgers
For decks and heavy exterior loads, the ledger connection is designed and placed before the pour. Never hang a deck off the foam alone.
Mark it on the plan
Show cabinet runs and TV walls on the drawings so the crew can add blocking before the drywall crew arrives.
Get a Real Number for Your Project
Send us your plans or a rough sketch. We price the ICF work from real wall areas, not guesses, and tell you straight if ICF is not the right fit.
Outside: Siding, Stone and Stucco
Vinyl, steel and fibre-cement siding screw directly to the webs. Many installers add vertical strapping first to create a rain screen gap, which we recommend on exposed Georgian Bay lots.
Brick and stone are heavy and need to sit on something. A brick-ledge block forms a concrete ledge in the wall, or the veneer sits on a ledge on the foundation. Ties fasten into the webs. Plan the ledge height before the pour.
Stucco and EIFS-style finishes go over the foam with a fibreglass mesh and a base coat designed for EPS. Use a complete system from one manufacturer, with drainage behind it where the system requires it.
Thin manufactured stone goes over a lath and scratch coat fastened to the webs, again with a drainage layer.
Below Grade and at the Grade Line
The foam above the ground needs protection from weed trimmers, sun and the odd lawnmower. Use a parge coat, a protection board or flashing from the top of the waterproofing up to the siding. Below grade, see ICF waterproofing.
Finishing Mistakes We See
- Solvent-based adhesives or caulks that eat the foam.
- Drywall screws that miss the webs and pop out later.
- Exposed foam left in a garage or basement, which fails inspection.
- No plan for heavy cabinets, then a scramble with concrete anchors.
- Siding installed tight to the grade with no protection for the foam.
Get a Real Number for Your Project
Send us your plans or a rough sketch. We price the ICF work from real wall areas, not guesses, and tell you straight if ICF is not the right fit.
Questions We Get
How do you attach drywall to ICF?+
Screw it into the plastic webs, which run vertically every 6 or 8 inches, usually with a bead of foam-safe adhesive as well. No studs or strapping are needed.
Do you need a vapour barrier on ICF walls?+
No. The EPS foam acts as the vapour retarder. Adding polyethylene can trap moisture and is not needed.
Can you hang kitchen cabinets on ICF walls?+
Yes. Add wood strips screwed to several webs before drywall, or fasten through to the concrete with proper anchors for heavy loads.
How do you put brick or stone on an ICF house?+
Use a brick-ledge block or a foundation ledge to carry the weight, and tie the veneer back to the webs. Plan the ledge before the pour.
Can ICF foam be left exposed?+
Not in living space, a garage or a basement. The code requires a thermal barrier, normally 1/2-inch drywall, over foam plastic inside the building.