Jim B ) said...

If I engage contractors or builder to rebuilding and enlarge
a house, what will be the percentage for labor and building
material?

There are a lot of factors that can effect this, as others have posted,
but a good rule-of-thumb is that you will spend $2 on labour for every
$1 in materials.

We build our own house, finishing about a year and a half ago, and we
did about 85% of the work ourselves.

In some areas, the materials/labour ratio was close to the rule of
thumb, in others it was hard to tell since the contract price was for
the total deliverables.

Shingling the roof was easy as we purchased the materials ourselves
(about $1600) and hired the labour separately (about $2200), so the
ratio was about 42% materials, 58% labour.

A few areas where we considered having the work done, but ended up
doing it ourselves, the chance to compare is a bit easier:

Windows:
total cost from supplier: $5300
two quotes for supply & install: $11,000 and $14,000
(about 37% to 48% materials)

Ceiling texture spraying:
total cost of supplies and equipment rental: $185
estimate for job: $750
(about 25% materials/equipment)

Framing:
cost of materials (excluding roof trusses): about $16,000
quote for labour (excluding roof): about $20,000
(about 45% materials)

I find the 1/3 materials figure a good rule-of-thumb for estimating as
actual figures tend to lean towards a slightly higher percentage for
materials, meaning that total costs tend to be estimated higher than the
come in at (e.g.: if materials are estimated at $1000, then labour is
estimated at $2000, for a total of $3000 -- but if the $1000 of materials
ends up representing 40% of the total, then the total is $2500)

--
Calvin Henry-Cotnam
"Never ascribe to malice what can equally be explained by incompetence."
- Napoleon
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