Guidelines for Part A where structural alterations are proposed
Important notes for Building Regulation Part A, Structural Alterations
Customer Guidance Note 02.
GUIDELINES FOR BUILDING REGULATIONS PART 'A' SUBMISSIONS WHERE STRUCTURAL ALTERATIONS ARE PROPOSED
The following information is very important. Please take the time to read it as it concerns your building regulations proposals.
Adhering to the basic requirements in these notes will limit delays in us examining and responding to your structural proposals. Insufficient structural information and badly referenced design submissions often demand extra processing time for your application and may result in the rejection of your proposals. Presenting your design proposals in accordance with these requirements will help speed up the processing of your application and help Building Control to deliver a much better service to you.
BASIC REQUIREMENTS
1. Floor plans at all relevant levels of the building should be submitted showing direction of span of the floor(s) and roof. Relevant section and elevation drawings will also be required. Relevant plans, section and elevation drawings will include information that will justify design loadings and sizing calculations for the proposed structural element(s)
2. All proposed structural elements should be clearly referenced both on the design drawings and in the design calculations.
3. The design drawings should show the size (and centres, in the case of timber joists) of all proposed structural elements.
4. Existing and proposed layout drawings will be required. The proposed layout drawing should clearly show the area(s) of proposed works.
5. Details of connections between structural elements (including end-bearing details) should be provided. Design calculations to justify the adequacy of these connections and end-bearings should also be provided.
6. Where ties are to be provided, these should be clearly shown.
7. It is strongly recommended that all design calculations are to be in accordance with the latest code of practice.
8. Structural engineer's (or designer's) contact details should be given, including telephone number, facsimile number and email address if available.
9. You are advised that chimney breasts should not be used for the support of new structural elements.
10. It is unlikely that any loads bearing onto a live chimney will be approved.
11. The allowable end bearing stress of a beam on old brickwork should be limited to 0.42 N/mm2.
12. In the absence of laboratory test results, the following typical values of allowable bearing pressure on virgin soil will be acceptable
- Brick earth / clay 80 - 100 kN/m2.
- Sand / ballast 150 - 200 kN/m2. Other values should be agreed with the building control officer where appropriate
13. When load bearing walls are removed, especially at the lowest floor level to create clear openings such as through-lounges, rear extensions etc, consider providing box frame(s) with adequate joint rigidity for the purpose of maintaining lateral sway stability/robustness to the structure. It is strongly advised that any stability contribution of adjacent properties are not to be considered in the assessment of the stability of the proposed structure.
14. For the purpose of controlling cracking in old / existing brick buildings, the total dead and live load deflection for beams supporting existing roofs and existing walls over new openings is to be limited to span/360 or 15mm, whichever is the lesser.
15. Timber floors offer limited restraint to steel beams. Positive fixings at say quarter points along the span of a beam are recommended to resist 1% of compression force in the flange as lateral load. As timber floors have limited diaphragm action, total force resulting from this restraint should be limited to 6 kN.
16. Where beams are loaded eccentrically, design for torsion or provide torsion restraint.
17. Retaining walls to light wells adjacent to pavements may need to be checked for the effect of wheel loads and consent obtained for the Highways Division. Consult our highways division for design loading requirements.
18. Basement construction: Basement retaining walls should be designed in accordance with the appropriate design code of practice. Mass concrete storey height basement walls are not recommended. Shorter mass concrete underpins should be justified by calculations or sized in accordance with The Building Regulations 1991 Approved Document A, clause 1C25b on page 23. Sequence of excavation and construction work will be required.
19. Loft extension: Provide adequate decking to the flat roof and ties to the party walls. The flat roof is to be constructed in such a manner as to provide adequate diaphragm action capable of transferring shear from one end of the roof to the other. Any alternative design must show adequate justification of roof stability.
GENERAL NOTES
Make sure before commencing any building work, that you get planning approval (if needed), Party Wall agreement (where required), and approval from highways engineers if you intend to deposit building materials/skips or erect a scaffold on the road or footpath or cut into/build highway retaining structures.
You are reminded of the importance of building to your approved plans. Should you wish to make any changes you may need to get written consent from both building control and development control (planning) before proceeding, which may take time, so early notification is vital.
Please inform building control at the relevant stages of work. Notice must be given at least 24hrs (48hrs for commencement) before you need the inspection, this may be done by telephone if you wish. Call 020 8753 1081, and ask to be put through to building control. In normal circumstances, we will aim to respond that day to inspection requests received before 10:00am.
