Frequently Asked Questions

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.
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.
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.
Fox Blocks con­tain a min­i­mum of 40% recy­cled con­tent by weight.
  • Fox Blocks do not off-gas and are not man­u­fac­tured using any gas­es that deplete the ozone or are harm­ful to the envi­ron­ment.
  • Fox Blocks require low embod­ied ener­gy to man­u­fac­ture.
  • Fox Blocks do not con­tain any mate­ri­als, that pro­mote mold or mildew growth.
  • Fox Blocks are an effi­cient con­struc­tion method there­by reduc­ing the amount of con­struc­tion waste, dust and air pol­lu­tion in the build­ing process.
  • Build­ing with Fox Blocks will save on heat­ing and cool­ing costs because less air is exchanged between the out­side and inside of your home. This also means a small­er more effi­cient HVAC unit is required for the home.
  • Fox Blocks are sus­tain­able. They will not rot or dete­ri­o­rate for the life of your home.
  • Fox Blocks pro­vide a secure, durable, com­fort­able, long last­ing build­ing
Yes, every com­po­nent of the Fox Blocks form itself plus the con­crete and rein­force­ment bars are recy­clable.
Yes, Fox Blocks has a brick ledge form and the xLer­a­tor ledge rein­force­ment that is designed to sup­port mason­ry. Fox blocks also has a tieKey acces­so­ry which is a specif­i­cal­ly made as a mason­ry tie, to be insert­ed through the form into the con­crete.
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.

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.

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.
Prod­ucts are not rat­ed or cer­ti­fied under the LEED pro­gram. The over­all build­ing is eval­u­at­ed and assigned a LEED rat­ing. In the selec­tion of build­ing mate­ri­als for a LEED design, Fox Blocks have many ben­e­fits that can enable, enhance or direct­ly con­tribute toward LEED points for the project.

The clear R‑Value of an Fox Blocks is R22, how­ev­er cur­rent Ener­gy codes rec­og­nize the lack of ther­mal bridg­ing in an ICF and the con­tri­bu­tion of the mass con­crete on the influ­ence of the ther­mal per­for­mance. Whole wall cal­cu­la­tions indi­cate a Fox blocks wall assem­bly pro­vides an R24 rat­ing.

The con­tin­u­ous dou­ble lay­er (inside and out­side) of insu­la­tion, the elim­i­na­tion of ther­mal bridg­ing and min­i­mal air infil­tra­tion through the mass con­crete wall assem­bly, allows Fox Blocks walls to per­for­mance in the high per­for­mance wall assem­bly cat­e­go­ry. Com­plet­ing the enve­lope with ener­gy effi­cient win­dows and doors and roof insu­la­tion, Fox Blocks homes can eas­i­ly meet and exceed ener­gy code require­ments and exceed the min­i­mum require­ments for Ener­gy Star and Ener­Guide. A Fox Blocks struc­ture requires 44% less ener­gy to heat and 32% less ener­gy to cool.

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.

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.
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.
Ener­gy Star does not eval­u­ate or rate insu­la­tion prod­ucts. Every Fox Blocks home when test­ed by an Ener­gy Rater, can meet and exceed the Ener­gy Star home stan­dards and achieve a 5 Star rat­ing and a HERS’ score well below the min­i­mum Ener­gy Star require­ment of 85, or in Cana­da, high­er than an Ener­Guide rat­ing of 80.
No. The char­ac­ter­is­tics of an ICF wall with the mass con­crete and the EPS insu­la­tion pro­vide the required vapor per­me­ance to meet build­ing code require­ments as a vapor bar­ri­er.

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.

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.

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.
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.
EPS does not off-gas. Fox Blocks forms do not and nev­er have con­tained any CFC or HCFC prod­ucts. The forms are made by a steam process that uti­lizes pen­tene gas’ as a blow­ing agent. The blow­ing agent dis­si­pates from the prod­uct with­in 48 hours of man­u­fac­tur­ing. Fox Blocks forms are odor­less, do not dete­ri­o­rate, and do not off gas.
Fox Blocks are com­pat­i­ble with all exte­ri­or fin­ish mate­ri­als and sys­tems – sid­ing, stuc­co, mason­ry veneer, sim­u­lat­ed stone, etc. The attach­ment of cer­tain exte­ri­or fin­ish­ing sys­tems is rec­om­mend­ed with exte­ri­or grade screws fas­tened into the exposed or con­cealed webs.
No, EPS is a closed cell foam and does not act like a sponge or absorb water.
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.
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.