Ci Builder Company

Hollow floors, also known as suspended or timber floors, are simply timber joists suspended across and supported by load bearing walls under the floor. the ends of these timber joists are built into, or suspended by joist hangers from the external walls of the property.

there are suspended concrete floors but we do not cover these here as they are more typically used in new build projects as they tend not to be economical under around 50m2. here we are going to focus on floating timber floors (all these terms are interchangeable).

When cables run through insulating material they need to be thicker to be able to handle the same current.

i have seen some old installations with under size cables to start with so i would advise you to get some one on site to advise rather than remote on a forum.

Are these vents venting directly into the rooms or just into the underfloor area?
if they are only venting the underfloor area then i would suggest not reducing the underfloor ventilation. instead you might consider insulating and reducing draughts from under the timber floors.
there are plenty of threads on this topic.

as the kitchen is an extension, the builder may have provided a channel under the concrete floor for the continuation of the under floor ventilation for the rest of the house. have a look at this link for a better understanding, and scroll down to the photos:

I would expect a call-out fee to be a component of the whole job; i wouldn't expect it to be paid if no work was carried out.

otherwise where do you draw the line? if they simply choose not to do the work because they don't want to, should the customer pay? or if they get lost on the way and never turn up?

A fuse board does not need to be replaced due to its age. if & when the installation undergoes an electrical inspection & test, it is then found to be non-compliant with the british standards' minimum requirements, then & only then will it need replacing. c. i builder company