Frequently Asked Questions

A stud find­er typ­i­cal­ly uses the den­si­ty of mate­ri­als to locate studs. The polypropy­lene (plas­tic) web mate­r­i­al will show up on high qual­i­ty den­si­ty stud find­ers. Note, the webs in Fox Blocks are spaced at 8″ (200 mm) on cen­ter and will be con­tin­u­ous ver­ti­cal­ly on each side of the wall.

No, EPS is a closed cell foam and does not act like a sponge or absorb water.
Most ICF blocks share com­mon fea­tures and ben­e­fits. Fox Blocks, as a com­pa­ny, pro­vides 30 years’ expe­ri­ence in prod­uct devel­op­ment, doc­u­men­ta­tion, test­ing and train­ing, as well as ver­sa­til­i­ty in the line of prod­ucts to meet all appli­ca­tions. The key dif­fer­ence comes in the exper­tise and sup­port you get from Fox Blocks. Fox Blocks is the leader in insu­lat­ing con­crete form con­struc­tion – proven in over 100,000 com­mer­cial and res­i­den­tial projects across North Amer­i­ca. Exten­sive resources and sup­port sys­tems are avail­able to ensure your project’s suc­cess from start to fin­ish. Please vis­it our web­site www.Fox Blocks​.com to review our project gallery and find more detailed doc­u­men­ta­tion on the prod­ucts and the appli­ca­tions. Fox Blocks also pro­vides a toll free num­ber for Cus­tomer and Tech­ni­cal Sup­port 8773692562.
Yes, mar­gin­al­ly high­er on the ini­tial cap­i­tal costs, but, it is a record­ed fact that Fox Blocks high per­for­mance homes out per­form in com­fort and oper­at­ing costs over a wood framed home. These cre­ates month­ly cost sav­ings for the life cycle of the Fox Blocks home.

Build­ing with Fox Blocks ICFs pro­vides you with a high per­for­mance wall sys­tem for the foun­da­tion and above grade walls. Build­ing any high per­for­mance home, with either ICFs or con­ven­tion­al wood fram­ing, has many fac­tors that define the end cap­i­tal costs.

What addi­tion­al mate­ri­als and labor are required to make a con­ven­tion­al foun­da­tion equiv­a­lent to an Fox Blocks ICF foun­da­tion which exceeds ener­gy code require­ments in most loca­tions? Con­ven­tion­al wood fram­ing requires con­sid­er­ably more mate­r­i­al, insu­la­tion and atten­tion to air seal­ing to make it qual­i­fy and per­form as a high per­for­mance wall. All of this, for con­ven­tion­al con­struc­tion, adds mate­r­i­al and labor costs to the over­all project. Fox Blocks ICFs pro­vide a sim­ple method to build high per­for­mance walls that pro­vide ongo­ing ben­e­fits from the high insu­la­tion val­ues and mass con­crete walls that are ener­gy-effi­cient and pro­vide cost sav­ings for the life cycle of the build­ing.

Com­par­ing cost per square foot between con­ven­tion­al con­struc­tion and ICFs for a high per­for­mance build­ing, is like com­par­ing apples to oranges. To devel­op con­struc­tion costs, more detailed infor­ma­tion is required, for instance the num­ber and size of open­ings, the shape and size of the home, the region­al costs for mate­r­i­al and labor, etc. If you have a project you’d like us to review and pro­vide a mate­r­i­al esti­mate, Fox Blocks would be hap­py to have one of our rep­re­sen­ta­tives con­tact you. Please com­plete and sub­mit a lead infor­ma­tion sheet on the web­site or call Cus­tomer Ser­vice.

Taper Top forms are specif­i­cal­ly designed to pro­vide a larg­er bear­ing sur­face along the top of the wall. Typ­i­cal­ly, the increased bear­ing sur­face may be used to sup­port mason­ry, floor or roof loads. Taper top forms are used in the tran­si­tion from ICF to wood frame con­struc­tion and the taper top form would be the top form on the wall.
No, ICFs in gen­er­al are cov­ered in the build­ing code and Fox Blocks ICF has a prod­uct eval­u­a­tion report that con­firms the prod­uct and appli­ca­tions meet the require­ments of the respec­tive build­ing codes in the USA and Cana­da. These reports are avail­able on our web­site.

All ICF walls below grade, that have hab­it­able space on one side (base­ment), must have a water­proof­ing / damp­proof­ing mem­brane installed. For walls that do not have hab­it­able space on one side (crawl space, frost walls, etc.) the EPS can be left exposed to the earth. The EPS will not dete­ri­o­rate when exposed to the earth.

A blow-out’ is a break in the form, gen­er­al­ly due to the pres­sure from the liq­uid con­crete dur­ing the con­crete place­ment and/​or con­sol­i­da­tion. Fox Blocks ICFs are designed to main­tain a high safe­ty fac­tor of pres­sure from the liq­uid con­crete. Dam­aged forms or fail­ure to sup­port areas where forms have been cut leav­ing a large area of EPS between the web sup­ports may cause a blow-out. Over con­sol­i­da­tion may also cause a blow-out.

Fox Blocks rec­om­mends the Pre-Place­ment Check­list be reviewed for all wall assem­blies pri­or to the place­ment of con­crete, to find poten­tial prob­lem areas and install addi­tion­al strap­ping or sup­port to pre­vent blow-outs. Gen­er­al­ly, for an Fox Blocks form, the size of a blow-out may be lim­it­ed to the EPS between the webs, 6″ or 8″ wide by the height of one form. If a blow-out occurs, the con­crete pour moves to anoth­er area on the wall, the hole is patched by replac­ing the EPS, installing wood sup­port over the area, and then resum­ing the pour.

Fox Blocks rec­om­mends that all installers using Fox Blocks ICFs com­plete a Fox Blocks train­ing pro­gram to ensure they have a bet­ter under­stand­ing of the basics. How­ev­er, for first time installers, it is pre­ferred that a Fox Blocks trained, expe­ri­enced installer inspect the instal­la­tion pri­or to place­ment of con­crete and assist in the place­ment of the con­crete, as they are famil­iar with work­ing with con­crete and can ensure the build is struc­tural­ly sound and safe and the walls are con­sol­i­dat­ed prop­er­ly, built straight and plumb.
The ICF blocks are held in place with either low expan­sion spray foam or a met­al starter track. The bracing/​alignment sys­tem, typ­i­cal­ly installed after the 4th course of block, also sup­ports the ICFs in place. Once the con­crete is in the wall there is no con­cern with the forms mov­ing. The con­crete is con­nect­ed to the foot­ing with rein­forc­ing dow­els.
Fox Blocks offers the most com­pre­hen­sive installer train­ing in the indus­try. We can train your con­trac­tor or help you locate a trained installer in your area.

ICFs pro­vide a rein­forced con­crete wall which is designed to spe­cif­ic engi­neer­ing prin­ci­ples. Typ­i­cal res­i­den­tial con­struc­tion, per the applic­a­bil­i­ty lim­its in the build­ing code, allows walls 10′ (3 m) high or less between lat­er­al sup­ports (floor and roof con­nec­tions). Below grade walls must have a min­i­mum 6″ (150 mm) con­crete core. In some regions, an 8″ (200 mm) con­crete core is the min­i­mum allowed thick­ness for below grade walls.

The 4″ (100 mm) form can­not be used below grade as a foun­da­tion wall. The 4″ (100 mm) form may be used for above grade walls up to a max­i­mum of 10′ (3.0 m).

The 6″ (150 mm) form, above grade, is lim­it­ed to approx­i­mate­ly 14′ (4.2 m) in height. Walls high­er than 14′ (4.2 m) must use an 8″ (200 mm) or larg­er form.

Typ­i­cal res­i­den­tial con­struc­tion will use 6″ or 8″ con­crete core size blocks. Project spe­cif­ic engi­neer­ing may allow for some core thick­ness to span ver­ti­cal­ly high­er than these pro­posed guide­lines.

Yes, but you will notice a light dust­ing on the sur­face and a yel­low­ing dis­col­oration of the forms. This does not indi­cate any detri­men­tal effects to the ICFs. We do sug­gest, that if the exte­ri­or fin­ish is not going to be installed with­in around a 3 month peri­od or more, the forms be pro­tect­ed from UV rays by installing a tem­po­rary build­ing wrap type mate­r­i­al. The pow­dery film must be removed with soap and water before the appli­ca­tion of a syn­thet­ic stuc­co fin­ish or water­proof­ing mem­brane.

Fox Blocks has con­duct­ed numer­ous fas­ten­er tests for pull-out strength and shear capac­i­ty for var­i­ous fas­ten­ers – screws, ring shank nails and sta­ples into the plas­tic webs. The rec­om­men­da­tion for inte­ri­or and exte­ri­or appli­ca­tions of fin­ish mate­ri­als is for the use of screws which pro­vide the best hold­ing capac­i­ty into the plas­tic webs or fas­ten­ing strips in the forms which are iden­ti­fied on each block.

The EPS insu­la­tion does not pro­vide any hold­ing capac­i­ty for fas­ten­ers.

The con­crete must cure for a min­i­mum of 7 days and the foun­da­tion wall must be lat­er­al­ly sup­port­ed, mean­ing the floor sys­tem is installed sup­port­ing the top of the wall. All below grade water­proof­ing / damp­proof­ing must be installed.
Yes, if the fol­low­ing cri­te­ria is avail­able for the design of a con­crete lin­tel (beam) over the open­ing – con­crete lin­tel depth min­i­mum 16″ (400 mm) or more with no point loads. Larg­er open­ings would require an engi­neered design.
No, the EPS has no struc­tur­al capac­i­ty to sup­port any loads. Wood sill plates must achieve the required bear­ing from the con­crete with­in the ICF. A wood plate that can­tilevers 13 over the EPS and bears 23 on the con­crete is allow­able. This can be done with a min­i­mum 2 x 6 plate. If a 24 plate is required, a taper top form should be used to extend the con­crete under the plate.
Fox Blocks has devel­oped the Fox Buck specif­i­cal­ly to frame open­ings such as win­dows and doors. The Fox Buck pro­vides insu­la­tion around the open­ing plus sup­port for the attach­ment of the win­dow or door.
The assem­bly and place­ment of con­crete may take the same time as to build with con­ven­tion­al meth­ods. The advan­tage with Fox Blocks is that the walls are now insu­lat­ed, have a vapor and air bar­ri­er installed and are ready for fin­ish­es once the win­dows and roof are installed. These ben­e­fits will save weeks and/​or months depend­ing on the size of the projects.
Yes, con­sol­i­da­tion of the con­crete is one of the key ele­ments in the place­ment of con­crete in an ICF wall. Fox Blocks rec­om­mends inter­nal vibra­tion with a pen­cil vibra­tor, quick­ly in and slow­ly out.
The con­crete is nor­mal strength, min­i­mum 2500 psi (20 MPa) per build­ing codes. The mix design spec­i­fies a small­er aggre­gate and high­er slump than con­crete typ­i­cal­ly used for floors. Most Ready-Mix sup­pli­ers are famil­iar with an ICF con­crete mix design.
To alle­vi­ate the pres­sure from the liq­uid con­crete, the con­crete is placed in lay­ers or lifts’. The first lift is lim­it­ed to 4′ (1.2 m) of con­crete around the perime­ter of the build­ing. This allows approx­i­mate­ly one hour for the con­crete to set-up before con­tin­u­ing with the next 4′ (1.2 m) lift. The low­er lift pro­vides sup­port for the next lift as the con­crete is placed con­tin­u­ous­ly around the build­ing in con­sec­u­tive lifts to the top of the wall.
No. Spec­i­fi­ca­tions in the Amer­i­ca Con­crete Insti­tute (ACI) do not lim­it the max­i­mum dis­tance con­crete can free fall. Engi­neer­ing stud­ies and reports have shown that free fall from up to 35′ doesn’t reduce con­crete qual­i­ty and there is no evi­dence of seg­re­ga­tion or weak­ened con­crete strength. ICF con­crete design calls for a high slump mix which assists in reduc­ing seg­re­ga­tion.
Yes. The forms insu­late the con­crete and enhance the cur­ing process. The top of the forms, or exposed con­crete areas will need to be cov­ered, tem­porar­i­ly, with insu­la­tion to pre­vent the exposed con­crete from freez­ing. Fox Blocks projects can be con­struct­ed any time of the year, no delays for cold weath­er.