Hi Crabtree,
How long have you got ?
It might be more appropriate for TFEC members to provide some answers to your questions as this type of issue falls within their balliewick.
There are significant and well recorded historical precedents as to what types of timber frame design will survive over the longer term.
Timber frame buildings do not usually fail catastrophically but instead tend to slowly yield to the ravages of time.
Fire will affect a timber framed building more slowly than an equivalent size balloon (stud) frame building since it will take longer for the primary components to fail as the fire gradually wastes their section. Design for fire resistance has more to do with providing sufficient escape time for occupants than trying to preserve the structure itself.
Computer modeling is probably the greatest step forward yet made in building structure design. This facility is particularly useful where custom or esoteric designs are being pursued since it helps identify potential problem areas within a frame but also don't forget that it also identifies those components that are not highly stressed and could therefore be made from lower grade materials thus with good design engineering it might be possible to produce a more cost effective design that could be sold more affordably or alternatively provide a higher profit margin to a builder without the need to unduly compromise safety.
Most people do not want to pay for design or engineering and some believe that they are quite capable of handling all technical issues by themselves and up to a point this can be true i.e. when a frame is being built to a building pattern that has passed the test of time then the scope for encountering major problems are probably greatly reduced. It is where the uncertainty or consequence of failure becomes higher that engineering input should be sought.
The issue of legislation must also be considered in that some states / provencies / countries reserve certain building design matters to engineers and it would appear foolhardy to ignore those requirements.
Applying good old fashioned common sense combined with experience is a pre requisite to undertaking any safe building programme but raises the issue of how a person is able to aquire experience and get to know his own limitations without harming himself or others arround him who might have had no say in the decision making process.
Building timber frames is a complex process and I have seen more than my fair share of building solutions with which I have not been particularly happy. Its a terrible feeling when a person is smiling ear to ear proudly displaying their work and inside you are thinking "OMG". How do you tell them ? Should you tell them ? Will they thank you ? Will they hate you ?
The longer term solution lies with bodies like the TFG and CF where free exchange of thoughts, ideas, concerns, and solutions will help to spread knowledge and understanding of timber framing issues and practices in so doing will hopefully improve the general levels of personal safety and building performance.
These are complex issues and cannot really be done justice on a short post on a bulletin board.
Regards
Ken Hume P.Eng
http://www.kfhume.freeserve.co.uk