The Building Conservation Directory 2021

PROTECT ION & REMEDIAL TREATMENT 4.1 133 C AT H E D R A L C O MM U N I C AT I O N S T H E B U I L D I N G C O N S E R VAT I O N D I R E C T O R Y 2 0 2 1 Tower 19 at Hythe in Kent. However, Tower 24 has been aided somewhat in this respect by the sea defences which have been installed at Dymchurch. The effect these defences have on the tower’s setting and significance is perhaps less beneficial, but they are certainly protecting it. Nevertheless, Tower 24 does suffer from significant building defects. Archive research suggests that during the Ministry of Works’ restoration in the 1960s the render, noted at the time as ‘modern roughcast’, had failed. The replacement render we see today is crazed, cracked and certainly causing water ingress. It is cement based and much too hard, as well as not having any proper finish, such as limewash, to help reduce rainwater penetration. In addition, the false ashlar joints are lines of weakness where the render has cracked and it is apparent that moisture is travelling through these fissures. The walls on the seaward side are up to 3m thick, which means that any moisture present may be trapped for a long time, with little chance of escape. While replacement of the render would definitely help with the water ingress (and egress) as well as being desirable aesthetically, it was also one of the most expensive options considered. Ventilation is another concern. Although the towers were designed with louvred shutters, some, such as Tower 24, were fitted with sash windows during their period as domestic dwellings. Originally two fireplaces would have provided heating which, combined with the effective ventilation supplied by the louvres, would have mitigated a great deal of the moisture we find inherent in the management of the building today. The tower is no longer in constant occupation and when it is, it is not used the way it was designed to be, further aggravating the situation. A further complication is that the towers were actually designed to collect rainwater and to store it for the stationed soldiers. The different towers have different means of storing and/ or disposing of the water including the Wish Tower in Eastbourne which still retains today its fine subterranean brick-vaulted cistern. The roof of Tower 24 is also presenting problems of water ingress. It appears to have a flat roof but this is in fact a gun platform or terreplein and its primary function was to support the cannon and soldiers during a battle (see cross section). The terreplein falls towards the internal downpipes and logic suggests that some form of waterproof coating would have been required to make the design viable. Although considerable research has been conducted on these towers, it is surprisingly hard to establish definitive proof of any roof coating. Outline drawings are available in the National Archives as well as in the Kent Library, but none found to date are sufficiently detailed to answer this question. Of course, if evidence for a waterproof coating was found, it might mean a different approach was taken to the conservation of these fascinating monuments. Some anecdotal references have been quoted in texts suggesting that the towers may have once been covered in lead, which does perhaps seem logical as the internal downpipes are formed in this material. However, consultations within Historic England determined that none of the Inspectors of Ancient Monuments ‘have ever found any firm archive evidence for lead coverings to south east martello parapets, or know of any towers that retain any firm evidence for an original (or early) lead parapet covering.’ One interesting observation on Tower 24 raises at least the possibility that lead was used on the roof. The roughly pitched masonry detail evident against the finely tooled ashlar of the Firing Step suggests a coarse modification. The stone would have left the quarry/banker shop with an upstand, and the detail has been removed by someone with much cruder tools than the original mason. The purpose of the upstand could have been for a lead roll to form the back gutter against the parapet. Of course, the upstand could have been simply to help the water find its way into to the collection system. The 1960s restoration works at Tower 24 removed a coating of bitumen which was recorded at the time as a later addition. It is understood that by 1850, the Royal Engineers intended a general refurbishment of the towers and it is possible that this is when the bitumen or asphalt was applied at Dymchurch. The neatly carved upstand would have proven an impediment to an effective waterproof asphalt layer and was therefore roughly pitched off prior to the work. In the context of the 2019 works, much firmer documentary evidence than this would have been required to even consider any such intervention to a scheduled monument. One paper which has been helpful in understanding the construction detail of the tower is Substance and Practice, Building Technology and the Royal Engineers in Canada by Elizabeth Vincent. Although This image of Martello Tower 19, which was undermined by waves, gives an indication of the robust construction of the towers which were built of solid coursed brickwork. (Photo: Tom Bosence) ThecrackedsurfaceofMartelloTower24showingareasofmossgrowthinitsfalseashlarjoints(Photo:TomBosence) The roughly pitched masonry detail evident against the finely tooled ashlar of the Firing Step suggests a coarse modification. (Photo: Tom Bosence)