WHY ARE THERE WOOD ROOFS ON CONCRETE BUILDINGS?
Until now, users of Insulated Concrete Form (ICF) have had little choice about using wood trusses, engineered and dimensioned lumber, and plywood sheathing to build their pitched roofs. The ICF manufacturers advertise about all the advantages of concrete inside their Expanded PolyStyrene (EPS) in-place insulation forms compared to traditional wood stick framing. Then their presentations just gloss over the unfortunate reality that the same condemned wood framing has to serve as the entire roof and ceiling structural system for their “concrete” homes.
But this disappointing problem is about to disappear, and the launching of ICF construction further into mainstream residential and commercial markets is about to happen. CASTROOF is the process that will replace wood framing in the roofs and ceilings of ICF buildings. Very soon, all of the tremendous advantages of ICF construction will be realized throughout the entire building – walls, ceilings, and ROOFS!
Before CASTROOF is presented, consider the current state of an important part of the ICF industry. Presently, there are a few different methods of EPS decking (flooring & roofing) which mold a (reinforced) concrete I-beam shape to support horizontal loads. The manufacturers may also provide a “tilting” option for their poured-in-place concrete which is lifted into a vertical wall position after hardening. The strength of the designed and reinforced shape easily supports loads imposed when vertical. So, why can’t these methods be used for traditional sloped roofing configurations also?
The answer is the difficulty of retaining the concrete’s position when it is on an angle (or pitched position) in its near liquid form. The effects of gravity would cause the concrete, even very low slump formulas, to flow down the slope of the roof during placement and finishing. Any attempt to vibrate (consolidate) the placed concrete for improving the reinforcing performance and density (strength) would quickly cause the placed concrete to slide down the EPS system and fall to the ground.
There are however, a couple of strategies for EPS decking as a pitched roofing method. First, the horizontal poured-in-place EPS decking concrete could be consolidated, then finished with a standard roof shape, hardened (hydrated), and then lifted up into a pitched position. There would likely be some complicated connections of reinforcing members at the intersections at the ridge, valley and wall lines, but a sloped concrete roof would be possible. Secondly, roof pitches could be designed with much less slope than standard 3- or 4- in 12 truss framing ratios. Finishing lower slump concrete in near-horizontal positions can be completed with consistent success. The appearance of a near smooth or an imprinted texture could become acceptable for tract and custom building resulting in concrete homes with concrete roofs.
Unfortunately, the current literature from EPS decking manufacturers does not indicate that market demands have motivated them toward these options. While there may be projects under development where these methods are employed, the efforts and achievements are not well publicized. Practical implementation and technology limitations may also limit the use of these procedures.
CASTROOF REPLACES WOOD WITH CONCRETE
CASTROOF is a process and system that solves the dilemmas described above and claims the following successes for pitched or sloped (including vertical) poured-in-place installations:
The CASTROOF molds will completely and securely hold concrete designed mixtures, with as much slump as you could want, pumped right into final position and shape;
The CASTROOF molds form the concrete into many different traditional shapes: two-piece clay tile, slate, concrete tile, wood shake, cedar shingles, and others;
The CASTROOF supporting methods securely position the molds above the EPS decking material for the concrete to be placed and consolidated within the space between;
The CASTROOF molds and their supporting system are so strong that they will support the weight of workers before and after the concrete is placed;
The ridge, rake, and eaves of the roof have mating and matching molds to make the appearance of the CASTROOF details to appear exactly like a standard piece-by-piece roof material application;
The CASTROOF molds are re-useable for many roofs in the same or different floor plans;
The CASTROOF interconnecting parts secure the positioning and effectiveness of the reinforcing components;
The CASTROOF patent covers the use of the system in vertical, sloped, and inverted positions applications such as poured-in-place retaining walls shaped like wood siding, shiplap, or brick materials;
The CASTROOF molds can be placed and secured without special skills or supervision;
The CASTROOF molds and fittings can be used in new ICF construction, and with new lighter-weight materials for re-roofing existing buildings;
All the advantages of the EPS floor and decking system including accesses for wiring and lighting fixtures, plumbing lines, mechanical air channels, and drywall attachment means remain available and unchanged when CASTROOF is used above them;
The CASTROOF process eliminates the need for wood truss and conventional wood framing materials and connecting hardware on top of concrete walled buildings and promotes the use of EPS flooring products and systems;
Span distances engineered using standard EPS decking computations need little if any adjustments for pitch and roof style shape. The existing engineering of standard wall/roof intersections is unchanged by the addition of the CASTROOF shapes of the upper surface.
WHAT IS THE FUTURE SURE TO BRING?
The strength and quality of harvested lumber will continue to decline.
The price of lumber, engineered or milled, will keep rising and the supply will keep dwindling.
The affects of mold, wood dry rot, termites will continue to negatively impact the traditional light-framing methods.
Steel framing, intended to replace wood framing will continue to increase in cost.
The cost of labor for traditional framing of wood or steel will continue to rise.
Concrete remains as one of the most plentiful and market stable building components.
Strong winds and hurricanes will continue to blow the shingles and tiles off of roofs.
The cost of roofing materials, especially those rooted in asphalt and oil will continue to rise, a lot.