This article has now been updated and replaced by Tolerances tables in Build 184.
A CONSTRUCTION TOLERANCE is an allowable variation in something that can be measured. These may be:
- the permitted variation from a given dimension or quantity
- the range of variation permitted in maintaining a specified dimension
- a permitted variation from location or alignment.
While these tolerances are a permitted deviation from perfect, the aim is always to be accurate when constructing and finishing a building. Taking everything to the outer tolerance limit may make achieving quality difficult for following trades.
SITUATION | ACCURATE TO WITHIN: | REFERENCE |
---|---|---|
BUILDING SET-OUT | ||
Location on site | 15 mm of the specified location on a site plan | NZS 3604 |
Building footprint | 1/200th of the length, up to maximum of ±5 mm of the specified dimensions | NZS 3604 |
Location of walls within building | 1/200th of the length, up to maximum of ±5 mm of the specified dimensions | NZS 3604 |
Deviation from vertical | 15 mm per 2-storey height (5 mm per 2.4 m) | NZS 3604 |
CONCRETE SLAB ON GROUND | ||
Deviation from prescribed finished floor level | 10 mm in any one room or space | NZS 3109 |
Surface level | ±3 mm in any 3 m of length | NZS 3109 |
ELEMENT | SITUATION | ACCURATE TO WITHIN: | REFERENCE |
---|---|---|---|
SUSPENDED FLOORS | |||
Piles | Concrete piles verticality | 15 mm per m of height | BRANZ |
Timber piles verticality | 10 mm of vertical in the first m above ground and within 20 mm of vertical over their total length | BRANZ | |
Driven timber piles | 15 mm of vertical for every m of length | NZS 3604 | |
Bearers and joists to horizontal | 5 mm for every 10 m; 10 mm in total for lengths over 10 m | NZS 3604 | |
Framing | Bearers and joists straightness | ±5 mm per 1 m | BRANZ |
Bearers and joist parallelity | ±5 mm per 3 m | BRANZ | |
Floor plane levelness | A slope of no more than 1:200 | MBIE | |
Suspended floor deflection | 1/360th of span maximum | BRANZ |
References to MBIE in the tables refer to the MBIE Guide to tolerances, materials and workmanship in new residential construction 2015, this is available from www.building.govt.nz.
SITUATION | ACCURATE TO WITHIN: | REFERENCE |
---|---|---|
TIMBER QUALITY | ||
Bow | 15 mm in a 2.4 m length of 50 mm thick framing (35 mm for a 3.6 m long member) | NZS 3631 |
Crook | 10 mm in a 2.4 m length of 100 mm wide framing (15 mm for a 3.6 m long member) | NZS 3631 |
Twist | 5 mm per 100 mm of width in a 2.4 m length of 50 thick framing (10 mm for a 3.6 m long member) | NZS 3631 |
TIMBER ROOF FRAMING | ||
Vertical elements | Straight to within ±5 mm for every 2.4 m rise in height | NZS 3604 |
Horizontal elements | Straight to within ±5 mm in lengths up to 10 m; 10 mm in total for lengths over 10 m | NZS 3604 |
TIMBER WALL FRAMING | ||
Deviation from: | ||
| 15 mm maximum | NZS 3604 |
| 5 mm for lengths up to 10 m; 10 mm in total for lengths over 10 m | NZS 3604 |
| 5 mm for lengths up to 10 m; 10 mm in total for lengths over 10 m | NZS 3604 |
| ±6 mm for every 3 m in any direction | NZS 3604 |
Inter-storey relative displacement of loadbearing walls | 5 mm for vertical alignment | NZS 3604 |
Permitted bow in studs at corners | 2 mm in any 2.4 m length | NZS 3604 |
Permitted bow in studs | 6 mm gradual bow permitted | NZS 3604 |
Verticality of frames | ±5 mm for every 2.4 m rise in height | NZS 3604 |
Alignment of wall framing | 1.5 mm for every 1.3 m or 6 mm over 3 m using horizontal straight edge | NZS 3604 |
FLOORING | ||
Finished floor | Slope no more than 1:200 | MBIE |
5 mm maximum deviation in any 10 m length; 10 mm in total for lengths over 10 m | BRANZ | |
Level to within ±5 mm within a single room or space | BRANZ | |
Flooring – individual sheets or boards | Flat and straight to within ±6 mm for every 3 m of length | BRANZ |
Note
This article has now been updated and replaced by Tolerances tables in Build 184.
Download the PDF
Articles are correct at the time of publication but may have since become outdated.