Notch so much .....!
Notch so much ….
Inappropriately cutting a hole as this guy has done or a notch other than in specified areas can lead to a joist being weakened to such a degree that collapse might occur.
Technical Guidance Document of the 1997 Building Regulations on Part A Structure offers clear guidance on where to drill a hole or cut a notch. It says as follows:
Notches and holes in simply supported floor and roof joists should be within the following limits:
(a) notches should be no deeper than 0.125 times the depth of a joist and should not be cut closer to the support than 0.07 times the span, nor further away than 0.25 times the span,
(b) holes should be no greater diameter than 0.25 times the depth of the joist, should be drilled at the neutral axis, should not be less than three diameters (centre to centre) apart and should be located between 0.25 and 0.4 times the span from the support, and
(c) the horizontal distance between any hole and any notch should not be less than the depth of the joist.
This is for domestic dwellings where the joists have a depth of not more than 250 mm a structural engineer need not be consulted provided:
Where a hole and a notch are made in the same joist they should be at least 100 mm apart, and where a hole is made the adjacent holes should not be closer than three times the maximum recommended diameter.
It is imperative that surveyors get to inspect the joists at first fix plumbing and electrical work stages and ensure that any service penetrations are not cut, bored or notched in excess of the above limitations.
While surveying existing buildings surveyors should watch for:
- Excessive movement on floors.
- Creaking floors in bathrooms and en-suites.
- Proximity of toilet relative to internal soil stacks with particular attention to direction of joist span and positioning of WC and stack.
- Vibrational movement from pipes beneath flooring.
- Recently refurbished bathrooms where the layout has been altered or fittings placed in new positions.
- Where ensuites are added as an afterthought.
- Level platform shower trays (wet rooms) added in to an existing 1st floor bathroom.