Lesson 11
 Timber
framed structures are common in
New Zealand. They comprise of timber
studs, plates, bearers, beams, rafters,
purlins and custom fabrications at the
connection points i.e joist hangers, bolts
 If
the building is predominately timber
framed a price can be sought for a prenail
construction. This is where the frames are
constructed off site and then installed as
component elements.
 Alternatively the each piece of timber is
measured and then priced on a unit rate
estimate
 Small


v large quantities
Consider the overall project. There maybe lots of
repetition but production rates can be affected
by the complexity of the project and the
connection details
Geographic location

Availability of material and delivery charges are
affected by the location of the project. You must also
consider if the material needs to be protected/ stored
when it arrives on site
 Labour

availability
Skilled craftsmen are required to efficiently
erect a timber framed structure. Need to
consider availability of labour and travel times
when pricing projects
 Seasonal

affect on work
Timber framed structures can be erected in all
seasons however the weather can effect the
method of installation and erection


Excessive moisture may cause the effect the wood to
swell making proper fitting difficult
Hot dry weather lower moisture content and causes to
shrink which causes connections to be excessively tight
when moisture content is returned to the wood.
 Scope

of works
As an estimator you need to understand the full
extent of the works. Consideration must be
taken for phasing work, working with other
trades, temporary utility locations and access.
 Calculating

labour constants
Depending on the labour constants used either
price as individual rates or average cost per man
hour
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Lead carpenter
Carpenter (2 no)
Labourer (2no)
Total
Average cost/man hour
$55.00/hr
$100.00/hr
$56.00/hr
$211.00/hr
$42.20/hr
 Calculating

These are typically sourced from timber
merchants or the contractors main database.
Special CSQ’s can be offered for larger projects.
 Calculating

material costs
equipment costs
Most skilled carpenters will provide their own
equipment ie nail guns, drop saws etc. However
specialist equipment will either be costed under
carpentry items or in the p & g section of the
tender
Example


If the length and height of a wall is known and
the centres of the studs are known then the
quantity of timber can be calculated if the m2
area of the wall is the only item given
The following method can be used for calculating
the number of bolts or other connections
Example



The length of a wall = 20m
The height is 3.0m
The centres of the studs are at 600 c/c
No of studs required are 3.0/.60 = 5+ 1 for the end
TOTAL = 6 no studs
Example

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If bolts are required at 1200 c/c along the base
plate.
Total no of bolts required 20/1.2 = 16.60
= 17 + 1
end
= 18 no
If joist hangers are required for rafters at 400
c/c along a roof line of 15m
Example


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
If joist hangers are required for rafters at 400
c/c along a roof line of 15m
Total no of joist hangers 15/0.40 = 37.50
= 38 +1
end
= 39 x 2
both
ends
Example





If bolts are required at 1200 c/c along the base
plate.
Total no of bolts required 20/1.2 = 16.60
= 17 + 1
end
= 18 no
If joist hangers are required for rafters at 400
c/c along a roof line of 15m

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100 x 50 timber joist fixed to timber plate
Materials
100 x 50
$3.00/m
Nails allow 2kg/m3 ($1.20 kg/m3)
2 x $1.2 x .05 x .1
$0.01/m
Sub total
$3.01/m
Delivery say 5 %
$0.15/m
Sub total
$3.16/m
Wastage
7.5%
$0.24/m
Total
$3.40/m


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
100 x 50 timber joist fixed to timber plate
Labour
0.14 hr/m @ $42.20 =
$5.98/m
Total
$9.31/m
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Other considerations
Unloading and distributing is included in the
labour rate or it is an additional item in the p&g
section
Nails are included in each individual unit rate or
are allowed for as a percentage of the total
carpentry costs (typically 10%)
Delivery can be costed separately and not
included in the unit rate

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
Cost estimates are broken down into different
sections. The main ones are trade or elements.
Construction costs are segregated into these
components for cost comparison or analysis.
Understanding what each component comprises
of helps to ensure that all items have been
included in the cost estimate

Summary of trade items

Site preparation and Demolition
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Demoliton, shoring of existing buildings
General site grading to required subgrades
Removal and relocation of ultility lines
Retaining walls to protect adjoining properties

Foundations
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Excavation of site subgrade and disposal of excavated
materials, backfilling and removal of surplus material
All necessary temporary work to support the sides of
the excavation and removal of ground water
All pile caps, tie beams, trenches, pad foundations
that are not part of the flooring system
Vertical Structure

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All columns and structural walls with the roughest
finish acceptable
Any necessary fire proofing

Floor and roof structure
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Floor slabs on grade including sand blinding and vapour
barriers but not waterproof membranes
All beams, trusses etc supported by the vertical
structure
Structural framing joist, rafters and decking of all
supported floors and roof – rough structural finish only
Necessary fire proofing
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Exterior Cladding
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Any non structural skin or curtain wall added to the
structure to enclose or finish the building
Any supporting framing or connections required for the
cladding
Any insulation
Waterproofing or damp proof membranes above grade
Non structural balconies, paparpet walls
Fascias, decorative bands or friezes
External window and doors/louvres including glazing
and hardware

Roofing and waterproofing
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Waterproof membranes on floors and walls including
skylights
Exterior and interior roofing insulation
Exterior applied membranes
All flashings and gutters/downpipes
Interior partitions, doors and glazing

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Non load bearing partitions
Sound insulation to partitions
Balustrades, rails screens
All interior doors and windows including glazing and
hardware

Floor, wall and ceiling finishes
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Floor coverings of all types
Bases or skirtings including finish
Any special finishes
Suspended ceilings and insulation above ceiling
Painting and other decorations
Function Equipment and specialities

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Any built in shelving and cabinetry
Protective guards and barriers
Prefabricated compartments and accessories

Stairs and vertical transportation

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Staircases and ramps complete with landings and
balustrading
Lifts and moving staircases/ramps
Dumb waiters or hoists
Plumbing system
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All sanitaryware and specialist plumbing items
Waste,soil pipes connected to the inside and outside
of the building
Drainage including sewer systems
Floor and roof drains and piping
Water treatment and storage including circulation

Heating, ventilation and air conditioning
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Heating, cooling and air cleaning equipment
All pipework and ducting associated with the above
Grills, dampers and exhaust fans
Electrical systems
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Main service from transformers, switch gear, panels
etc required for the building
All lighting fixtures, wiring and power circuits
Data cabling, sound and communication systems
Emergency power
BMS systems

Fire protection system
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Automatic fire protection and sprinkler systems
Site paving, structures and landscaping
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Retaining walls to support landscaping
Paving and curbs
Landscaping and irrigation
Site furniture
Fencing and rails
Lighting and drainage
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Contractors overheads and profit
P&G for the project – site establishment, storage
facilities, supervision, temporary services,
security insurance, bonds, permits
Margin – contractors margin for the total cost of
the project
Contingency for design development
Fluctuations