Some help with estimation of wall assembly cost?
We are in the process of designing a passive house and are working with PH certified architect/consultant. But for now, builder’s knowledge would be needed: a back of the envelope calculation for the cost /sf of this kind of wall assembly: fiber cement board w/ rain screen, fiber board, dense packed cellulose, OSB, dense packed cellulose, drywall. The wood framing will most likely be w/Larson trusses. The R-value we are trying to achieve is around 40. The house is a duplex with gross sf area of ~4500. Would be good to know the material & labor separately. Why do I need it? I want to compare to this option: hempcrete wall, where a cubic foot of hempcrete wall costs $16/f3, without framing nor labor.
Apart from yet unknown challenges how to reach passive house with hempcrete, how much would the cost be…?
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Lucyna,
There is no way that builders or architects who aren't working in your area can provide a construction estimate. Construction costs vary widely from one region of the country to another. The variations in costs are due to differences in materials cost, shipping costs, labor costs, and the availability of subcontractors.
Presumably, you are working with a designer and perhaps a general contractor. Residential designers and GCs should be familiar with construction cost estimating.
If you are building your own house and acting as your own GC, you will find estimating to be a challenge. The best way to estimate the cost of construction is to build a house that meets the specs that you are considering, keeping meticulous records. Builders who have done this for a few years can provide you an estimate.
If your designer has no capability of helping you with a construction cost estimate, it may be time to choose another designer, or to contact a design/build firm.
Hello Martin,
We do not have the builder or general contractor yet. This is a relatively early stage of the process. We know it would be good to have one (from attending several sessions in the PH conference on design-build) but realities don't seem to favor this. At this stage we are trying to evaluate which wall assembly to choose from which we would generate the construction details which would then go to the builder. BTW, our location is Pittsburgh, PA. Maybe somebody in this forum could give us the back of the envelope estimate.
Please listen to Martin. The sooner you get a builder on board the better. You are designing what will be a very challenging home to get right. You want the person building it to be on board for design. Back of the envelope pricing from someone uninvolved in the project will be worth the (re-used) paper it's written on.