It shouldn’t do. Most companies will do all the interior work first, and the last job to do will be creating the opening from the house to the conversion. A reputable company will make sure they cause as little disruption as possible during this time.
Llanfechain
Llanfechain is a tiny town as well as community in Powys, Wales, in between Llanfyllin as well as Llansantffraid-ym-Mechain on the B4393 road. Historically it was part of Montgomeryshire. Afon Cain goes through the village. It has a population of less than 500. Llanfechain can imply "church or church (llan) of the Cain valley" (from Llan ym Mach Cain suggesting "church in the field or plain of the Cain" to Llan ym Mechain and then Llan-mechain, which ends up being Llanfechain as a result of the common mutation of'm' to 'f' in Welsh). Nevertheless, it could also mean "little (fechan) church or parish (llan)". Punctuations of placenames vary significantly over time, so tiny variants such as chain/cain and also fechain/fechan are plausible. The name in the type Llanveccheyn is first run into in 1254. It has likewise been known as Llanarmon-ym-Mechain, ym-Mechain describes its area in the middle ages cantref of Mechain, hence 'Church of St Garmon in Mechain'.