Hi,

Recent posts about timber physiology and conversion were in my mind when Anne Ree called yesterday to tell me about a cottage that she had just viewed in Purley, Berkshire, England. She sent me a few digi pics to ask my opinion on certain matters and this was interesting since here was 400 year old testimony to past practice.



The first item to catch my attention was the gable end tie beam and I attach below a zoom in on this component.



This is an oak tie beam that has been halved and the pith or heart of the tree can plainly be seen wandering along the timber. The tree used to produce this component was obviously not very old maybe 30 - 50 years and so this must be made up from a high proportion of juvenille wood which we would expect might result in significant warp and decay but the proof is here that a timber that might well be classed as substandard today has endured in exposed service for at least 400 years. The secret to long term survival is of course the ability to dry quickly. The same cannot be said for the cross braces which have been covered by tiles. With a bit of luck these will have been attached with lime mortar which might help to remove any trapped water but the same cannot be said for the two rendered gable panels where portland cement has been employed. This is going to result in frost and water trap damage to both the timbers and the underlying soft red brickwork.

I was recently challeged hard on this forum as to how I can be so sure of my opinions in respect of timber framed buildings and the answer might well lie in having the opportunity close to home to examine the long term effects of design, function, tansformation, materials and workmanship where these factors can be observed first hand and conclusions drawn as to effectiveness in respect of all these factors.

This particular frame reflects function in the determination of bay lengths. We can see that a short 6 - 8 ft bay has been employed in which the chimney is currently located. This could be a smoke bay which would predate the insertion of a chimney or it could have been built from new to accomodate a chimney. The LH bay length is about 10ft and the RH about 12 ft. This building is equipped with sills and Anne tells me that these are now somewhat deteriorated. A scotch (dap) is visible in the main post to the LH of the porch at mid rail height and this indicates that this building has probably already had work done to repair or replace the sill and also right the building. Some of the infill horizontal noggin is not positioned in a regular fashion and this is most likely a cheap and chearful repair done by a brick layer rather than carpenter. The quality of timber used for the mid rails is pretty awful and the mortices at their connection with the main posts have now blown to reveal the under lying tenons. Despite this the building has survived long term and this can also be attributed to the large number of secondary timbers that were employed initially to frame windows, doors and infil panels which also help to provide secondary load paths to accomodate failures in main components. All the lesons needing to be respected to ensure the long term survival of a timber framed building are here for those who want to see them.

The height from the mid rail to top of wall plate indicates that this is not an open hall and was built with upper floors from the outset. We can thus probably confidently ascribe a date of later than 1550 but probably no later than 1600. The porch is positioned in front of the chimney bay and there will be a short entrace lobby immediatly behind the front door and a stair winding up the chimney on the far side. This style of house would thus be called a lobby entrance box frame.

I suppose if one see's enough of these kinds of buildings then eventually one becomes quite intuitive about what to expect and so here we have a building pattern that can be replicated with fairly good certainty of long term performance and with little risk accrueing to a carpenter builder even if he has to use sub standard materials and is unable to run calculations.

The result also just happens to be quite charming.

Regards

Ken Hume

Spamalot - Follow this link to an image of the Gilpin House...

http://www.tfguild.org/forums/ubbthreads.php?ubb=showthreaded&Number=21169#Post21169

I really am looking for help in identifying the name of this Tie and perhaps some idea if there is a region they are common to, on either side of the pond.

Stone houses and barns are quite common to this area, (unlike home) but I have yet to see another example that has these broken ties, or any embedded ties for that matter.

Hi Will,

I did read and examine your original post but found myself to be more than a little stumped for a name or experience of seeing another like that which can be seen at the Gilpen House.

At first sight this practice doesn't make a lot of sense but on further reflection it might well be good practice.

If we consider alternatives then the obvious one might be a continuous tie beam stretching from side to side. This would result in a plane of weakness at the integration line between the stone gable and the lower gable wall. Usually gables are less thick than the lower gable wall because they are not holding anything up and so there would be a real prospect of the gable simply falling out of place. The alternative might be to simply bury the wall plate in the end wall but because this would be so close to the surface of the masonary then there would be very little deadweight to develop sufficient holding power to resist outward thrust.

The picture would appear to illustrate a compromise between these 2 options such that the gable masonary remains reasonably stable and the wall plate is secured.

A better solution might be to run a tie beam or tie rod along the inside face of the gable but not burying this in the wall. This would leave a short cantilevered section of wall plate which would be carrying very little roof load. Have you been able to inspect inside to see if a tie beam / rod is in place ?

Making a join between masonary and timber is not easy. On my recent trip to Barbados I discovered that the timber windmill cap was secured to the masonary of the stone tower by a process of building a ring of 6 foot long vertical timbers into the 3 foot thick mill wall top and then securing the cap ring to same. Clearly this solution works but it is unable to be adequately inspected and as such must pose a continual worry to the owner / operators. The only reason I know this is because I saw a derelict mill wall with these timbers now exposed. I will try to dig out and post a photo of this feature.

I am meeting with some knoweldgeable building types in Oxford tonight and will raise this issue to see if others who live in the north west of that county have any experience of this technique. That part of Oxfordshire is built using predominately Cotswold stone walls with timber floor and roof so I might get a result.

Regards

Ken Hume

Hi Will and Ken

I would think that the embedded tie could be a variant of a dead man anchor. The interesting detail is the peg and to what the peg connects. If a hidden stubby tee at the end of the tie is present an effective tie could be produced.

The peg is the interesting aspect, and I do wish I could know what is going on in there. I haven't put a ruler to them,but it is on the large side, perhaps 1 3/4" and placement is the same on all of them, with all that end distance in the relish.

They have held up to time well (though one suggest some movement) despite some erratic repointing and parging over time, sometimes with portland in the mix, most of that and the predictable results happen lower down - I'd suspect the Ties are still bedded in lime mortar.