In a timber frame structure, all areas can be sealed using an air tightness membrane & tape. It is undeniably a much easier & therefore cheaper build process than with standard masonry construction. For example, the walls in a block built home are only airtight if an internal plaster is applied straight to the block work & spread evenly at full coverage. It’s important to keep this in mind if you intend to internally insulate to increase your u-value. There is an option to externally insulate your block build, however this would mean using insulated boards as your external walls rather than block which negates it’s purpose.
Another benefit of timber frame is that your wall cavity is left completely free to do it’s job & the thermal responsiveness of timber allows the build to heat & cool quickly. With block, self-builders are having to full fill their cavity in order to achieve the minimum Part L regulations. To achieve maximum levels of efficiency, internal or external insulation is required in a block build – both of which can cause significant problems. In comparison, timber frame benefits from a 100mm exterior leaf of block, open cavity (as it should be!) & a thermally responsive inner timber frame structure packed full with quality insulation & a complete airtight seal.