Let’s face it - you can’t and don’t want to specify every nail in a construction.
But reasonably detailed specifications will reduce your risk of getting substandard materials or workmanship. It also reduces the risk of disputes over the completed work quality since the standards for material type, quality, installation and workmanship are spelled out in black and white.
How detailed a spec should be depends on the complexity and requirements of the job. Even the simplest room renovation needs at least a basic specification and should include listing the products to be used by brand and model for just about every product and material to be used on the job. For paints and coatings, you will want to specify what prep work will be done and how many coats are to be applied.
For anything beyond that, you’ll want detailed a specification to support your design.
Your specification must cover all areas of the job, particularly those that are critical, such as:
- very costly, or costly to fix (such as the foundation)
- critical to the structural integrity of the project
- prone to problems (like cladding)
- or require specialized products or workmanship that may be unfamiliar to the tradespeople doing the job.
If problems show up after the work is done, you will be in much stronger position to get the work repaired if you have included detailed standards and finishes in the specification to fall back on.
Examples of products or systems that should always have detailed installation specs, and issues to cover in the specs, include:
- Foundations – Concrete mix, strength, reinforcing
- Concrete slabs – Concrete mix, strength, reinforcement, flatness, finish, expansion/movement joints, allowable cracks
- Roofing – Type, weight/thickness/warranty period of roofing; type of underlay, flashings, and fasteners. Carefully specify details for low-slope roofs, and for complex roofs with hips and valleys, detailing how valleys will be waterproofed. Get detailed material and installation specs for roofing materials such as metal, tile, slate, and composite materials.
- Windows and doors – Specify type, model, and energy efficiency. Also provide flashing details around doors and windows to prevent leaks.
- Skylights – Prone to leaking. Make sure installation follows manufacturers’ specs.
- Insulation – If you care about energy performance, you’ll need to specify this carefully.
- Wood flooring – Moisture content, substrate, fasteners, vapor barriers (over slab), finishes.
- Ceramic tile – Floor must be stiff enough - Pay attention to substrates, adhesives, and movement joints.
- Special construction for wind or seismic loads – This includes wind-resistant roofing, impact-resistant windows, engineered framing fasteners, and brace wall requirements.
- Metal components in coastal areas – Make sure that any exposed metal flashing, fasteners, or hardware is stainless steel, copper, special coated hot-dipped galvanized or aluminium. Other metals and finishes will not last long due to the corrosive power of salt spray.
If you know what you want, specify it. Do you want the nail holes filled with a color-matched putty on your natural woodwork? If so, put it in the specification.
While you can’t spec every last nail, there are times when you have to spec things as small as nails. Take, for example, nail size where it is critical and nail material type in different environments that have corrosive effects.
Using the proper type and size of nails and fasteners is often critical for cladding and framing or other engineered framing connectors, as well as with plaster board (to prevent nail pops), and many other building materials.
So, in many cases, it does make sense to specify the nails.
Last but not least, don't forget that you will need some general sections that describe the project and how you want the Contractor to act and behave while he is doing the project. So you want the Contractor to carry out only the work that you want done, on the right site, in the right way. The aim of general sections is to share knowledge of the project, allocate responsibility, define how to track what is going on and reduce surprises.
MASTERSPEC
The Masterspec system is designed to take the hard work out of specifying, from the simplest spec (with Masterspec Minor) to even the most complex construction projects with Masterspec Standard. Wherever possible we include ALL the information and alternatives you may need in a work section – it’s simply a matter of deleting what’s not relevant and refining the result.
This starts with the Q&A session when loading the section, designed to pre-edit your section and trim out extranneous detail.
It’s then a matter of filling in the correct products and details to match your design. Often these are included in the Green Guidance Notes (not available in Minor) in a work section, so make sure you check these – if you can’t see them, turn them on. Guidance notes in all Branded work sections (again, not in Minor) are developed with the manufacturer or supplier, so include all the specific information you will need.
You can then copy and paste the information into the clause knowing that the detail, the work section and the specification will be correct and include the relevant Building Code, NZ Standards and Industry Practice.
Our thanks go to buildingadvisor.com on whose information and articles we have based this guide. We have changed content to suit local materials, standards and construction practices.
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