Renovation work should begin with a detailed survey of the structure of the bungalow. If necessary, use a structural engineer to assess structural damage/condition, assess loadings, advise on the condition of foundations and roof, and advise on strengthening measures.

Undersized framing 

The existing framing found in bungalows is likely to be undersized for their spans when compared to the current requirements of NZS 3604 Timber framed buildings. However the native timbers used in the construction of bungalows generally had greater strength that the timbers used today, so in many situations undersized framing may not be a problem.

Where there is evidence of inadequate framing - such as sagging of floor and ceiling joists and rafters - options to remedy the undersized framing include:

• install strongbacks supported on load-bearing walls to provide support to rafters (Figure 1). It may be necessary to jack up the existing structure back to lift it back into line before the new framing is installed
• flitch a new member alongside the existing
• use engineered steel beams or LVL (laminated veneer lumber) beams where walls are being removed – these can be concealed in the roof space 
• install additional piles and bearers to the subfloor.

Figure 1: Strongback supporting ceiling joists.

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Other structural problems

Problems with foundations and floors

Many bungalows have uneven floors and need to be repiled or levelled. Some have inadequate foundation bracing, insufficient ground clearance, or insufficient subfloor ventilation causing dampness under the building.

Rot in framing

Rot is common when moisture is present. See rot and moisture for more.

Borer

Borer is unsightly and can sometimes affect a house’s structure. Read more.

Cracking or walls out of square

Common problems include walls that are out of square, cracked plaster ceilings, draughts, and the need to incorporate new insulation and linings. Read more.

Structural problems with brickwork

Common problems include cracked walls, rising damp, and failing mortar making chimneys or other structures unstable. Read more.