Cobbled Together

Chris has been working hard getting the floor of the cellar prepared for the mechanical and electrical systems installation (which will be covered in a future blog post).

Although most cellars are out of sight, out of mind, the cellar at Orleton Manor has been one of the centres of attention in this project. A great attention to detail has gone into the floors, walls and timber repairs in this most humble of service spaces - the cellar. It's a well-built space of stone walls and a cobbled floor that was incredibly damp and inhospitable before the works started. This was mainly due to the usual suspects of incompatible materials but also poor air flow across the space which has now been addressed.

Given that, by its nature, the cellar is underground, it is near impossible to completely and sympathetically stop the ingress of water. Yes, a modern tanking membrane or concrete box would stop the water penetrating into the space, but this would have dire consequences on the historic material behind. As with all historic buildings, the focus is on controlling the movement of water rather than stopping it completely - if you block one path, the water will take the next path of least resistance which could be even more damaging.

The system of works in place here is the removal of all the cement mortar pointing and its replacement with a very lime-rich, hot mix mortar, which has the ability to suck the moisture out of the wall and to its surface. This lime mortar will allow a small amount of moisture to permeate during the worst of the weather, but it will also allow it to dry naturally. If the cellar was particularly damp a couple of coats of lime wash would help, but we couldn't get away with it in this instance.

As the cellar is an enclosed space, that has less ventilation than the outside atmosphere, the water molecules don't have as much capacity to be removed through convection or evaporation.

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Traditional, solid walls primarily dry through water molecules being ripped from the surface by the wind; with the strong covalent bond acting like a chain and pulling out water from deep within the wall. We shall cover this off in more detail in another blog post.

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Therefore to aid the drying and improve the circulation in this cellar, we are using a pair of Vapour Flow fans. These work in tandem and are Autostat Smart Humidity controlled, heating air coming in from the outside and venting when the humidity gets too high.

To allow for tanks to be installed in the cellar, the floor had to be lowered. This gave us an opportunity to add some perimeter drainage to the walls and lay a limecrete floor. As the majority of the main floors in the manor are cast concrete and down for replacement, we will have much more information on the laying of replacement limecrete floors towards the end of Spring 2022.

Once the sub floors were completed, Chris took his time relaying some of the slabs and cobbles. The final scheme will be completed when the tank is in place.

We will revisit the cellar in another post looking at the chamber beam and ceiling repairs.

Plinth Walls to the Kitchen Wing

Given the weight of the frame and the fact that the plinth walls had been filled up with cement, with a cast cement up against them which contributed to the decay of the frame, the plinth was removed to facilitate the installation of the sole plate from the underside.

This traditional plinth was laid by Chris of Lawrence Masonry, using hotlime mixed in our pan on the back of the tractor. The stones were reinstated along with some new big stones which were missing, to take the weight of the frame. The largest of the stones were placed under each of the posts.

The final stonework will be pointed up once the weight of the frame is fully released onto the plinth

The first of a few flitches

A flitch repair certainly has its place within the armoury of conserving of a historic timber frame. The flitch in principle allows a greater retention of of historic material and is a mostly hidden repair, whereas a carpentry solution (if strong enough), would equate a high loss and a very obvious repair.

Flitch beam manufactured to match template

In this instance the flitch plate repair allowed one of the original timbers to remain in situ, in its primary location, maintaining its chamfers and stops whilst providing the structural integrity to the frame and floor. It is logical to think that if the timber was replaced or repaired then this would be adequate, but due to the large amount of timber notching, removal of structural elements the flitch is doing much more than the original timber.

This chamfer detail is an exact copy of the tower in Stokesay Castle

A flitch plate repair can be carried out in several ways, but is essentially it is a steel beam sandwiched between two slices of timber and bolted in position to provide extra strength and reducing the timbers deflection. Or in the case of this flitch, a T section of steel with mounting feet either end.

The moulded timber in question which was down for repair was ruptured at about 1/3 span of the beam, a scarf repair would have lost 1/3 of the timber plus a minimum of 2.5D (depending on the scarf) which would not have been acceptable, nor met the loading requirements needed for the building or the floor above. The new stainless steel plate spans from wall to wall through the beam so, as well as picking up the floor load, it also serves to tie the two walls together. Something the original timber was not doing!

Cutting the flitch rebate with a modified chainsaw

Reinforcing the beam with a hidden stainless steel T section allowed us to meet these structural requirements along with saving the maximum amount of historic material, yes the timber was cut along its back, but from the underside on show the timber remains historic with the tell tale signs of reinforcement through diamond pellets above the bolt holes.

Lowering the flitch into position

The old moulded beam in the play room can now breath a big sigh of relief now this steel is in place and hopefully admired for many years to come. This flitch was the easy one, we have another to do twice the size soon, watch this space!